South Lake Tahoe City Council
November 1, 2022

Electronic Written Comment #2
• A comment was made noting the welladvertised Evacuation Routes and having all first responders on the same radio frequencies
are absolutely critical. The commenter noted
they worked in natural hazards for FEMA for
twelve years.
• Comment noted. The City updated the evacuation
routes prior to the development of the LHMP update.

Subsequent updates to the evacuation plan and routes
will be reviewed as part of Mitigation Action W-9, which involves routine updates to City Evacuation Plan
including the development of procedures that identify
and address the needs of socially vulnerable
populations in the City.

Electronic Written Comment #3
• There was a comment made regarding visitors
in the Tahoe Basin: the situation where tourists
are allowed to travel into the basin during red
flag warnings and evacuation warnings needs
to be ended so that the community is safe and
has full access to the very few exit roads and
highways out of the basin. During wildfire
activity times and the threats of wildfire, high
winds, and other hazards, incoming traffic
needs to be stopped in Carson City,
• Comment noted. The City appreciates concerns
regarding visitors travelling into the Tahoe Basin during red flag warnings related to high winds and increased
wildfire threat given the limited evacuation roads in the region. These recommendations will be considered by
City staff in the implementation of Mitigation Action W9 related to the City’s Evacuation Plan. 494
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Gardnerville and Echo Summit as well as Hwy

88. Electronic Written Comment #4
• The commenter will provide input after they
attend the April 26 City meeting this evening.
• Comment noted. The City appreciates the time and
effort to provide feedback on the Draft LHMP.

Emailed Written Comment #5 (David Jenkins)
• The commenter thanked the City and
responsible law enforcement and safety
personnel for community disaster response
and protection support and their efforts
planning to address earthquake, flooding,
liquefaction and other hazards in the City.
• Comment noted. The City appreciates the time and
effort to provide feedback on the Draft LHMP.
• The commenter raised concern regarding
catastrophic wildfire susceptibility in the City
limits and how the recent Caldor wildfire
increased the focus on fire danger and fire
prevention needs in the City. The commenter
referenced an San Francisco Chronicle article
discussing the prospects of the wildfire
situation. Also noted was the need to not only
collaborate with other state and regional
agencies, but to promote government
advocacy from these other agencies either
voluntarily or with enforcement to better
protect the community
• Comment noted. The development of the City of South
Lake Tahoe LHMP update involved a multi-agency
stakeholder group from state, regional, and local
agencies and organizations. This included asking
stakeholders to provide specific input on mitigation
actions that would reduce or eliminate priority hazard
concerns in the City, related to earthquake, severe
weather, flooding, and wildfire hazards. As a result of the stakeholder engagement process, several of the
new mitigation actions or updated actions in the LHMP
include implementation support from other
government agencies, particularly those related to fuel reduction project implementation on federal and state
lands in and around the City.
• Fire Prevention. The commenter noted that
there are a large number of vacant parcels
owned by the USFS and CTC in the City that
are poorly maintained and that pose a wildfire
threat and the City must take steps to ensure
these properties are made fire safe. Suggested
mitigation actions include adding provisions
that require annual inspections on vacant
public lands within the City limits and that
Federal and State land managers implement
fire hazard reductions as an annual task
requirement.
• Comment noted. The mitigation strategy contains nine
different mitigation projects related to wildfire hazard reduction. Mitigation Action W-2 focuses on forest fuel reduction and defensible space maintenance within the
City. Mitigation Action W-2 includes two components:
1) fuel reduction projects to minimize the natural buildup of fuel in the forest properties within and surrounding the City, and 2) continuation of the Citywide Defensible Space Program for private properties in the City. While the fuel reduction projects would occur on large City-owned properties, these projects help
manage and limit fuels build up within the City.

Likewise, the City's Defensible Space Program is
managed by the City’s Fire Inspector and consists of
routine inspections on lots in the City. The goal of
Mitigation Action W-2 is to enhance the existing
Defensible Space Program to mitigate potential wildfire threats more effectively in and near the City by adding staff capacity to implement defensible space projects
on public and private lands in the City.

Similarly, Mitigation Action W-3 is an action carried
forward from the 2008 Mitigation Strategy that focuses
on continued cooperation between the USFS and CTC
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on how to best continue fuels reduction and maintain
the urban lot properties in the City. The City recognizes that this ongoing and routine fuels reduction work
needs to continue on these urban lots to reduce
wildfire threat, minimize adjacent and neighborhood
concerns, and promote safety.
• Water Supply. The commenter noted the need
to complete an assessment on water supply
and storage to adequately provide minimum
fire flow to all fire hydrants in the city limits
and ensure that the water agencies provide
fire hydrants where needed. The commenter
suggests the City should assist public and
private water providers to obtain funds to
upgrade municipal water systems to meet fire
response requirements and added the need to
examine efficiency issues related to
consolidation to determine cost-effective ways
to deliver drinkable water and adequate water
for fire suppression.
• Comment noted. The City recognizes the need to
support public and private water providers related to
upgrading municipal water systems. The STPUD was
one of the HMPC stakeholders involved during the
development of the City’s LHMP update. The City also
coordinated with the three small private water
companies in the City during the development of the
City’s LHMP update to integrate their water facilities
into the City’s Critical Facility database developed for the LHMP risk and vulnerability assessment. These
additional small private water companies include the
Tahoe Keys Water Company, Lukins Brothers Water
Company, Inc., and Lakeside Park Mutual Water
Company.

Additionally, Mitigation Action W-8 focuses on
enhancing reliability and availability of water
distribution for fire flow and to ensure appropriate
water pressure in the event of a wildfire. This action also focuses on continuing to work with water utility
providers, such as STPUD to ensure the water system
operations are reliable and provide adequate water for
fire suppression.
• Undergrounding of Utilities. The comment
points out the City must examine the costs
and benefits of undergrounding municipal
utilities within the city limits. Undergrounding
utilities ensures reliability of services during
winter weather events and avoids fire risk . The
commenter recognizing the cost associated
with undergrounding utilities, but states such
a program should be explored now to prevent
wildfire risk, radiation risk, and pollution.
• Comment noted. The City recognizes the need and
long-term benefit of undergrounding utilities
associated with new development. As such, the City
added another mitigation action in the mitigation
Strategy. Mitigation Action MH-5 involves
consideration of retrofitting utilities to below ground level and analyzing options with local utility providers.

As a new mitigation action, the City anticipates future communication and correspondence with local utility
providers, such as Liberty Utilities; such collaboration is forthcoming in order to fully examine the feasibility of retrofitting and undergrounding utilities in the City.
• Conclusion. The commenter stated that the
mitigation actions related to fire prevention,
water supply coordination, and the
undergrounding of utilities must be
considered by the City and incorporated into
the adopted General Plan. The commenter
emphasized the importance of adopting the
public safety actions if the City Council desires
to pursue them.
• Comment noted. The Draft LHMP acknowledges the
importance of mitigation actions focused on wildfire
prevention, drought and water supply related to fire
suppression and the benefits of reducing multiple
hazards by undergrounding utilities. As a result, several of these hazards were ranked significant concerns by
the HMPC and the community. In turn, the City
developed, selected, and prioritized mitigation actions focused on severe weather, wildfire risk, and reducing
energy shortages. These mitigation actions are
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summarized in Section 5.2.3, Mitigation Action Plan and in Table 5-3, Mitigation Action Summary.

The City also received and reviewed the article,
“California wildfires: Here’s when experts think fire
danger will peak in Northern California.”
Wood will produce a final Draft LHMP in June 2022 for Cal OES and FEMA Region IX staff to review and approve, contingent upon final adoption by South Lake Tahoe City Council.

3.3.4 Phase 4: Implement the Plan and Monitor Progress
Planning Step 9: Adopt the Plan
In order to secure buy-in and officially implement the plan, the plan will be reviewed by the Planning Commission and adopted by the South Lake Tahoe City Council on the dates included in the corresponding resolution in Appendix D: Adoption Resolution.

Planning Step 10: Implement, Evaluate, and Revise the Plan The true worth of any mitigation plan is in the effectiveness of its implementation. In the previous steps of the planning process the HMPC’s efforts have been directed at researching data, gathering information for the plan, and developing appropriate mitigation actions. Each recommended action includes key descriptors, such as a lead entity and possible funding sources, to help initiate implementation. An overall implementation strategy for the City’s LHMP is described in Chapter 0 Plan Implementation and Maintenance.

Finally, there are numerous organizations within the City of South Lake Tahoe’s Planning Area whose goals and interests interface with hazard mitigation. Coordination with these other planning efforts, as addressed in Planning Step 3, is key to the ongoing success of this plan and mitigation in the City of South Lake Tahoe and is addressed further in Chapter 0. A plan update and maintenance schedule and a strategy for continued public involvement are also included in Chapter 0. 497
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44 U.S. Code of Federal Regulations Requirement §201.6 Local Mitigation Plans (c)(2): [The plan shall include] A risk assessment that provides the factual basis for activities proposed in the strategy to reduce losses from identified hazards. Local risk assessments must provide sufficient information to enable the jurisdiction to identify and prioritize appropriate mitigation actions to reduce losses from identified hazards.

As defined by the FEMA, risk is a combination of hazard, vulnerability, and exposure. “It is the impact that a hazard would have on people, services, facilities, and structures in a community and refers to the likelihood of a hazard event resulting in an adverse condition that causes injury or damage.” The risk assessment process identifies and profiles relevant hazards and assesses the exposure of lives, property, and infrastructure to these hazards, as well as the vulnerabilities of a community. The process allows for a better understanding of a jurisdiction’s potential risk to hazards and provides a framework for developing and prioritizing mitigation actions to reduce risk from future hazard events.

This risk assessment followed the methodology described in the FEMA publication “Understanding Your Risks—Identifying Hazards and Estimating Losses” (FEMA 386-2, 2002), which breaks the assessment into a four-step process:

1. Identify hazards

2. Profile hazard events

3. Inventory assets

4. Estimate losses
In other words, this risk assessment evaluates potential loss from hazards by assessing the vulnerability of the City of South Lake Tahoe’s (City) population; services; critical facilities; and buildings and infrastructure. Data collected through this process has been incorporated into the following sections of this chapter:
• Section 4.1 Hazard Identification profiles the natural hazards that threaten the City Planning Area (Planning Area) and describes why some hazards have been omitted from further consideration. • Section 4.2 Asset Summary describes the methodology for determining the vulnerability of the Planning Area to the identified hazards.
• Section 4.3 Hazard Profiles and Risk Assessment discusses the threat to the Planning Area and describes previous occurrences of hazard events and the likelihood of future occurrences. All the hazards identified in Section 4.1 are profiled and assessed individually in this section. Research and information from the City of South Lake Tahoe HMPC is integrated into this section. This section also includes the identified vulnerability to each of the priority hazards, describing the impact that each hazard would have on the City. The vulnerability assessment quantifies (to the extent possible) using the best available information, assets at risk to hazards, and estimates potential losses. • Section 4.3.10 Human-Caused, Human-Health, and Climate-Related Hazards identifies the hazards that threaten the Planning Area resulting from human actions.

This risk assessment covers the entire geographical extent of the City of South Lake Tahoe, City limits, and in some cases critical facilities within the City’s water and wastewater service areas. This area is referred herein as the City’s Planning Area. The HMPC agreed that the City’s Planning Area for the LHMP update 498
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-2 should include the City limits, but for some hazards, the analysis accounts for critical facilities within the Sphere of Influence (SOI), as well as critical facilities across the state border in Nevada (e.g. casinos, etc.).

This assessment qualitatively discusses critical facilities outside the City’s limits with the exception of the wildfire risk assessment. A larger Planning Area was considered for wildfire hazards to ensure that all the City’s facilities and infrastructure are addressed in the risk assessment because some of these facilities were located outside the Planning Area. Instead, the assessment also qualitatively discusses critical facilities located outside the City’s Planning Area in Stateline, Nevada, as several of these critical facilities are key police and fire stations, medical care centers, and shelters for the larger community.

Additional information on the City’s Planning Area as it pertains to this plan is provided in Chapter 2, Community Profile.

4.1 Hazard Identification: Natural and Human-Caused Hazards 44 U.S. Code of Federal Regulations Requirement §201.6(c)(2)(i): [The risk assessment shall include a] description of the type…of all natural hazards that can affect the jurisdiction.

The first step in developing a risk assessment is identifying the natural hazards. The HMPC conducted a hazard identification study to determine the hazards that threaten the Planning Area. The identification of human-caused hazards is summarized in Section 4.3.10.

4.1.1 Methodology and Results
Using existing natural hazards data and input gained through planning meetings, the HMPC agreed upon a list of natural and human-caused hazards that could affect the City of South Lake Tahoe. Hazards data was examined to identify and assess the significance of these hazards to the Planning Area. The sources of data included information from the Cal OES, FEMA, the National Oceanic and Atmospheric Administration (NOAA), El Dorado County Office of Emergency Services, City of South Lake Tahoe and other sources as referenced in this assessment. The assessment also relied on the City’s 2008 Natural Hazard Mitigation Plan, which was originally included as an Annex to El Dorado County Multi-Jurisdictional Hazard Mitigation Plan (MJHMP). The current 2018 El Dorado County plan consists of a single-jurisdictional LHMP. The assessment also relies on relevant City planning documents, such as the City’s 2011 General Plan Health and Safety Element; the South Lake Tahoe City Code 2021; the City’s 2020 CAP, other adopted hazard mitigation plans in the region, such as Douglas County’s 2019 HMP; and numerous other policy and planning documents related to the Lake Tahoe Region, including the Lake Tahoe: State of the Lake Report 2021.

Table 4-1 below provides a crosswalk of the hazards identified in the General Plan 2011, 2008 Natural Hazard Mitigation Plan, 2018 El Dorado County Operational Area Hazard Mitigation Plan, 2018 El Dorado County Water Agency LHMP, and 2018 California State Hazard Mitigation Plan (SHMP). Numerous hazards were identified in the State and County plan, including four natural hazards and three humancaused hazards identified in the South Lake Tahoe General Plan Health and Safety Element. Natural hazards discussed in the South Lake Tahoe General Plan Health and Safety Element included fire hazards, seismic and geologic hazards, flooding hazards, and avalanche hazards. Human-caused hazards discussed included the use, storage, and transport of hazardous materials, airport hazards, and noise. Besides, nine natural hazards were discussed in the City’s 2008 Natural Hazard Mitigation Plan, including avalanches, dam incidents, drought, earthquake, flood, landslide, severe winter storm, seiches, and wildfire. The crosswalk was used to develop a list of preliminary hazards for the HMPC to evaluate which were most relevant to the City’s Planning Area.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-3 The significance of each hazard was measured in general terms and focused on key criteria such as frequency and resulting damage, which includes deaths, injuries, and property and economic damage. The natural and human-caused hazards evaluated as part of this plan include those that occurred in the past or have the potential to cause significant human and/or monetary losses in the future.

Table 4-1 Crosswalk with Other Hazard Mitigation Plans
Hazard South
Lake
Tahoe
General
Plan
Safety
Element
(2011)
City of
South
Lake
Tahoe
HMP
Annex
(2008)
Lake Valley
Fire
Protection
District
LHMP
(2020)
El Dorado
County
LHMP
(2018)
California
SHMP
(2018)
Agricultural and Silvicultural Pests and
Diseases
√
Air Pollution √
Aquatic Invasive Species √
Avalanches √ √ √ √ √
Dam Incidents/Failure √ √ √
Drought and Water Shortage √ √ √
Climate Change √ √
Earthquake and Geologic Hazards √ √ √ √
Energy Shortage and Energy Resiliency √
Epidemic/Pandemic/Vector-Borne
Disease
√
Flood: 100-, 200-, 500-Year Events √ √ √ √ √
Landslides: Debris Flows and Mudslides √ √
Sea Level Rise √
Severe Weather: Extreme Heat √
Severe Weather: Heavy
Rain/Thunderstorm/Lightning/Hail/Fog
√ √ √
Severe Weather: Heavy Snow/Winter
Storms
√
Severe Weather: Wind √ √
Soil Hazards: Erosion and Subsidence √
Tree Mortality √
Tsunami (Seiche) √ √ √ √
Volcano √
Wildfire √ √ √ √ √
Hazardous Materials Release √ √
Oil Spills √ √
Natural Gas Pipeline Hazards √
Radiological Accidents √
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-4 Hazard South
Lake
Tahoe
General
Plan
Safety
Element
(2011)
City of
South
Lake
Tahoe
HMP
Annex
(2008)
Lake Valley
Fire
Protection
District
LHMP
(2020)
El Dorado
County
LHMP
(2018)
California
SHMP
(2018)
Transportation Accidents √
Terrorism √
Cyber Threats √
Civil Disorder √
Hazards listed is based on the natural, technological, and human-caused hazards in the California SHMP.

In alphabetical order, the natural hazards identified and investigated for the City of South Lake Tahoe 2021 – 2026 LHMP include:
• Avalanche
• Dam Incidents
• Drought and Water Shortage (includes Tree Mortality and Extreme Heat) • Earthquake
• Flood: 100/500-Year Flood (includes Seiche Hazards)
• Landslides and Debris Flows: Soil Hazards
• Severe Weather: Heavy Rain/Thunderstorm/Hail/Lightning/High Wind • Severe Weather: Heavy Snow/Winter Storms
• Wildfire
The human-caused, human-health, and other climate-related hazards identified and investigated for the City of South Lake Tahoe 2021 – 2026 LHMP include:
• Public Health Hazards: Epidemic/Pandemic
• Energy Shortages and Energy Resiliency
Based on discussions at the early planning meetings and preliminary analyses, the following natural and human-caused hazards were eliminated from further consideration in this risk assessment because of a lack of past occurrences in the City of South Lake Tahoe at the time or based on minimal potential impacts. Certain hazards were also eliminated based on separate State and El Dorado County regulatory programs and planning documentation that thoroughly addresses the hazard profile. • Agricultural Hazards
• Air Pollution
• Aquatic Invasive Species
• Sea Level Rise
• Severe Weather: Extreme Heat
• Volcano
South Lake Tahoe is a semi-urban City surrounded largely by rural and undeveloped land uses in the unincorporated portion of El Dorado County that consist of both residential uses, open space, vacant, and forest lands. According to the South Lake Tahoe General Plan Update 2010 Draft Environmental Impact Report (DEIR), there were approximately 12,062 acres or 47.5 percent of federal lands within the City’s 501
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-5 Planning Area (SOI). (City of South Lake Tahoe 2010). Most of the lands outside the City’s Planning Area also consist of designated federal forest land. Few of these forest lands include agricultural uses, such as farms or livestock ranches.

Air quality and emissions within the South Lake Tahoe area are generated by a variety of sources, including stationary sources, such as fireplaces and heating systems to mobile sources, such as vehicles and truck traffic. The United States Environmental Protection Agency (USEPA), the California Air Resources Board (CARB), and the TRPA regulate air quality at the federal and state levels. The El Dorado County Air Quality Management District (EDCAQMD) is the regional agency with the authority to develop and enforce regulations for the control of air pollution. The Sacramento region, which includes all of Sacramento and Yolo counties, and portions of Placer, El Dorado, Solano, and Sutter counties is considered in “attainment” for all of the national standards of carbon monoxide, nitrogen dioxide, sulfur dioxide, and lead, with the exception of ozone and particulate matter (El Dorado County 2021). Given there are federal, state, and local laws and regulations in place for controlling air pollution in El Dorado County, in addition to air quality management plans administered by the CARB and EDCAQMD, air pollution hazards are not addressed in this plan.

Aquatic invasive species (AIS) are non-indigenous species transported to new environments through human activities. The introduction of non-indigenous species into Lake Tahoe’s unique freshwater environment can cause economic, human health, and ecological impacts. Invasive aquatic species are considered “invasive” when they threaten the diversity of native species or the ecological stability of infested waters. According to the Lake Tahoe Regional Aquatic Invasive Species Management Plan, there are nearly 30 non-native species established in the Lake Tahoe Region, including aquatic plants, fishes, invertebrates, and amphibians (TRPA 2014). Examples include Eurasian watermilfoil, an aquatic plant that has been spreading around the lake over the last 25 years; curlyleaf pondweed, which has begun to spread over the past decade; and Asian clams, which are common and present in increasing numbers around Lake Tahoe. Known past occurrences related to AIS in the City were mostly identified near the public beaches and within the Tahoe Keys waterways. AIS is currently addressed by the TRPA EIP. The Lake Tahoe AIS Program aims to prevent, detect, and control AIS in the region in collaboration with the Tahoe Resource Conservation District. They implement the program through the Watercraft Inspection Program, AIS Control programs and projects, and specific goals outlined in the Lake Tahoe AIS Management Plan.

Given the TRPA EIP has several AIS programs in place, this hazard was not addressed in this plan.

Energy shortage hazards can include energy disruptions related to electricity, renewable energy, natural gas, and gasoline and diesel fuels. Based on the energy types, electrical power outages, both planned and unscheduled disruptions can result in cascading hazards related to traffic, economic losses, other utility disruptions, and public health hazards. Climate change is also expected to bring more frequent and intense natural disasters, which could result in planned or unscheduled power outages or energy shortages. Energy shortages and energy resiliency, specifically Public Safety Power Shutoffs (PSPS) are discussed as a secondary hazard impact and in the vulnerability assessment in the Severe Weather: Winter Storms/Heavy Snow and Severe Weather: Thunderstorm/Hail/Lightening sections of this chapter. Energy shortages and energy resiliency is also profiled, including a brief vulnerability assessment focused on the consequences of power outages due to winter snowstorms, high winds, and wildfire events.

The City of South Lake Tahoe is over 190 miles from the coastal areas along the Pacific Ocean. Therefore, sea level rise and related coastal hazards are not addressed in this plan. Similarly, given the high elevation of the City, annual summer temperatures, and the few past occurrences of high heat days, severe weather hazards related to extreme heat were not addressed in this plan. 502
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-6 Volcano hazards were also not addressed in this plan. According to the 2018 California SHMP, only ten volcanic eruptions have occurred in California in the last 1,000 years and the likelihood of another eruption in the state is low (Cal OES 2018). Of the 20 volcanoes in the State, only a few are active and pose a threat (Cal OES 2018). Of these, the Long Valley Caldera and Mono-Inyo Crater Volcanic Region is the closest volcanic region to the City, and while it has been known for substantial geothermal activity, there are no past occurrences associated with the volcano. Given this volcanic field is approximately 90 miles to the south and El Dorado County is not listed as one of the counties within the volcano hazard zone, volcano hazards were not addressed in this plan.

The City acknowledged natural gas pipeline hazards, oil spills, radiological incidents, as well as transportation accidents associated with these hazards. Gas pipeline hazards are addressed as a secondary hazard associated with earthquakes in the vulnerability assessment. Oil spill and radiological accidents were not further evaluated in this plan, as there are not any oil pipelines or oil wells in the City, and few areas are at risk of radiological accidents according to the HMPC. Other human-caused hazards, such as terrorism, and civil unrest or disturbances were considered and discussed during HMPC meetings, but because they are addressed in the Emergency Operations Plan (EOP), they were not discussed in detail in this plan. Hazardous material incidents were also discussed by the HMPC, but because these hazard incidents are already administered and managed by the County’s Department of Environmental Management, the Certified Unified Program Agency (CUPA) Program they are not further addressed in this plan. The County’s CUPA Program manages environmental and emergency management programs, including Hazardous Materials Release Response Plans, the California Accidental Release Prevention (CalARP) Program, Spill Prevention, Control, and Countermeasure Plans (SPCCs), and Hazardous Waste Generator programs. The County’s CUPA Programs provide a range of existing mitigation projects to minimize the risk associated with the storage, use, and transport of hazardous materials. Many of the human-caused hazards are also addressed in other City plan documents (e.g. South Lake Tahoe General Plan Transportation Element).

4.1.2 Overall Hazard Significance Summary
Overall hazard significance was based on a combination of geographic extent, probability of future occurrences, and potential magnitude/severity. Climate change considerations are discussed qualitatively in each hazard profile, specifically on whether it is anticipated to have a low, medium, or high influence on future impacts. The individual ratings shown in Table 4-2 are based on or interpolated from the analysis of the hazards in the sections that follow.

Table 4-2 City of South Lake Tahoe Hazard Significance Summary Hazard Geographic
Extent
Probability
of Future
Occurrences
Magnitude/Severity Overall
Significance
Avalanche Extensive Highly Likely Limited Low
Dam Incident Limited Unlikely Negligible Low
Drought Significant Likely Limited Medium
Earthquake Significant Likely Catastrophic High
Flood Significant Likely Limited High
Landslide and Debris Flows: Soil
Hazards
Limited Highly Likely Limited Medium
Severe Weather: Heavy
Rain/Thunderstorms/Hail/Lighting/Hi
gh Winds
Extensive Highly Likely Limited Medium
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Extent
Probability
of Future
Occurrences
Magnitude/Severity Overall
Significance
Severe Weather: Heavy Snow/Winter
Storms
Extensive Highly Likely Critical High
Wildfires Extensive Highly Likely Catastrophic High
Public Health Hazards:

Epidemics/Pandemics
Extensive Occasional Critical High
Energy Shortages and Energy
Resiliency
Extensive Highly Likely Limited High
Geographic Extent
Limited: Less than 10% of planning area
Significant: 10-50% of planning area
Extensive: 50-100% of planning area
Magnitude/Severity
Catastrophic—More than 50 percent of property severely
damaged; shutdown of facilities for more than 30 days;
and/or multiple deaths
Critical—25-50 percent of property severely damaged;
shutdown of facilities for at least two weeks; and/or
injuries and/or illnesses result in permanent disability Limited—10-25 percent of property severely damaged;
shutdown of facilities for more than a week; and/or
injuries/illnesses treatable do not result in permanent disability
Negligible—Less than 10 percent of property severely
damaged, shutdown of facilities and services for less than 24 hours; and/or injuries/illnesses treatable with first aid Overall Significance
Low: minimal potential impact
Medium: moderate potential impact
High: widespread potential impact
Probability of Future Occurrences
Highly Likely: Near 100% chance of occurrence in
next year or happens every year.

Likely: Between 10 and 100% chance of occurrence
in next year, or a recurrence interval of 10 years or
less.

Occasional: Between 1 and 10% chance of
occurrence in the next year or has a recurrence
interval of 11 to 100 years.

Unlikely: Less than 1% chance of occurrence in
next 100 years or has a recurrence interval of
greater than every 100 years.

FEMA’s Hazus 4.0 Loss Estimation Tool
Hazus Multi-Hazard Loss Estimation tool (Hazus-MH) is FEMA’s standardized method for modeling and estimating potential losses from earthquakes, floods, strong wind-caused events, and hurricanes. For the purposes of this plan, Hazus Version 4.0 was used with Geographic Information System (GIS) software to estimate economic and social impacts from the occurrence (or potential occurrence) of natural hazards (FEMA 2018a).

Hazus-MH provides tabular outputs as well as graphic and illustrative results of identified high-risk areas due to the profiled hazards of interest, with reports summarizing losses or damages from structures and critical facilities, populations affected or at risk, and debris generated from an event. Hazus 4.0 is a key component of the pre-disaster planning process and is used for mitigation and recovery, given its ability to estimate potential losses and damages in a city, county, and multi-regional context. For this LHMP, Hazus-MH was used to estimate effects from a probabilistic 2,500-year earthquake scenario as well as a USGS ShakeMap-based deterministic scenario, and the software is referenced in the dam incidents and flooding sections to point out methodologies applied to the vulnerability assessments as indicated in Hazus-MH loss calculation procedures (e.g. the FEMA flood depth-damage functions per the Benefit-Cost Analysis application) (FEMA 2018b). For more information on the earthquake scenarios processed with Hazus 4.0, refer to Section 4.3.4 Earthquakes.
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4.1.3 Disaster Declaration History
One method the HMPC used to identify hazards was researching past events that triggered federal and state emergency or disaster declarations in the Planning Area. Federal and state disaster declarations may be granted when the severity and magnitude of an event surpass the ability of the local government to respond and recover. Disaster assistance is supplemental and sequential. When the local government’s capacity has been surpassed, a state disaster declaration may be issued, allowing for the provision of state assistance. Should the disaster be so severe that both the local and state governments’ capacities are exceeded, a federal presidential emergency or disaster declaration may be issued allowing for the provision of federal assistance to help disaster victims, business, and public agencies.

The federal government may issue a disaster declaration through FEMA, the U.S. Department of Agriculture (USDA), or the Small Business Administration (SBA). FEMA also issues emergency declarations which are more limited in scope and without the long-term federal recovery programs of major disaster declarations (Farm Service Agency 2018). The quantity and types of damage are the determining factors in the type of declaration issued. This section focuses on state and federal disaster and emergency declarations.

The City of South Lake Tahoe is among many communities in California that are susceptible to disaster.

Details on federal and state disaster declarations were obtained by the HMPC, FEMA, and Cal OES and compiled in chronological order in Table 4-3.

Table 4-3 City of South Lake Tahoe and El Dorado County State and Federal Disaster Declarations, 1950-2021
Event/ Hazard Year Disaster # Declaration Type
Fire 1961 - State Proclamation
Storms 1963 - State Proclamation
Storms 1963 - Federal Declaration
Storms 1964 183 State Proclamation
Storms 1964 183 Major Disaster Declaration
Flood 1965 183 Major Disaster Declaration
Flood 1969 - State Proclamation
Flood 1969 253 Major Disaster Declaration
Flood 1970 - Major Disaster Declaration
Flood 1970 - State Proclamation
Freeze 1972 - State Proclamation
Storms 1975 - State Proclamation / Local Emergency
Drought 1977 3023 Emergency Declaration
Fire 1979 - State Proclamation
Flood 1980 - State Proclamation
Flood 1986 758 Major Disaster Declaration
Storms 1986 - State Proclamation
Severe Storm(s) 1995 1044 Major Disaster Declaration
Severe Storm(s) 1995 1046 Major Disaster Declaration
Storms 1995 - State Proclamation
Flood 1997 - State Proclamation
Severe Storm(s) 1997 1155 Major Disaster Declaration
Fire 2004 2532 Fire Management
Hurricane 2005 3248 Emergency Declaration
Severe Storm(s) 2006 1628 Major Disaster Declaration
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Severe Storm(s) 2006 1646 Major Disaster Declaration
Fire 2007 2700 Fire Management
Storms 2008 - State Proclamation
Fire 2014 5081 Fire Management
Storms 2017 - State Proclamation
Storms 2017 - State Proclamation (second time)
Severe Storm(s) 2017 4301 Major Disaster Declaration
Flood 2017 4305 Major Disaster Declaration
Flood 2017 4308 Major Disaster Declaration
Severe Storm(s) 2017 - Local Emergency
Severe Storm(s) 2019 4434 Major Disaster Declaration
Biological 2020 3428 Emergency Declaration
Biological 2020 4482 Major Disaster Declaration
Fire 2021 5413 Fire Management
Fire 2021 3571 Emergency Declaration
Fire 2021 4619 Major Disaster Declaration
Fire 2021 - Local Emergency
Source: 2018 California State Hazard Mitigation Plan, FEMA, 2016 El Dorado County Hazard Mitigation Plan Most disaster declarations are issued on a county-wide basis. In some limited instances, a city or area within a county is specifically designated. El Dorado County has received 42 declarations between 1961 and 2021, 25 of which were federal disaster declarations, including one fire management assistance, 15 were state proclamations, including one storm event in 1975 that received both the state proclamation and local emergency, and two were local emergencies. Of the 42 declarations, 18 were associated with (severe) storms, 10 were associated with flooding, and nine were associated with fire. Freeze and drought both received 1 declaration. The County also received 1 declaration related to Hurricane Katrina and two declarations related to the COVID-19 pandemic.

Since 2012, there have been 13 drought declarations issued by the Secretary of Agriculture for El Dorado County, eight of which were “Fast Track Secretarial Disaster” designations; refer to Section 4.3.3 on drought hazards for more details on previous occurrences of drought events. According to the Secretary of Agriculture, a Fast Track designation is for a severe drought and provides an automatic designation when any portion of the county meets the severe drought intensity value for eight consecutive weeks during the growing season.

This combined federal and state disaster history suggests that El Dorado County (and the City of South Lake Tahoe) experiences a major event worthy of a disaster declaration every 1.5 years. The County has a 69 percent chance of receiving a disaster declaration in any given year. Further, a review of these events helps the City identify risk reduction targets and ways to improve its capabilities to avoid large-scale hazard events in the future.
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4.1.4 Climate Change Considerations Summary
Climate change is an increasingly important factor now
affecting all phases of the disaster management cycle.

The City of South Lake Tahoe acknowledges that climate
change is occurring and has been supporting
sustainability planning through various initiatives over the past decade. In 2017, the City Council adopted a
resolution to achieve 100% renewable electricity by
2032, which equates to a 50% reduction in emissions by
2030, and an 80% reduction in emissions by 2040. The
City is also transitioning to 50% municipal renewable
energy by 2025 and 100% renewable energy for
municipal operations by 2032. They were the 26th City in the United States to make this commitment. The City has also initiated and implemented various other
sustainability efforts, including municipal facility energy efficiency upgrades, solar installations, a polystyrene regulation and plastic bag ban ordinance, zero waste
initiatives, and various sustainable business goals.

The City’s focus on addressing climate change was further underscored by the development of their first CAP, which was adopted by the City Council in October 2020. The CAP serves as the long-term plan to reduce greenhouse gas (GHG) emissions from community activities and includes actions to prepare for the impacts of climate change. The City is now in the implementation phase and prioritizing and implementing various emission reduction strategies, based on funding and community support.

The CAP contains a section that summarizes local climate change impacts that are specific to the City of South Lake Tahoe and El Dorado County. Data from the web-based Cal-Adapt tool were used to summarize the projected changes through the end of the century. Cal-Adapt is a scenario planning tool that was developed by the California Energy Commission and the University of California, Berkeley Geospatial Innovation Facility. The Cal-Adapt tool uses global climate simulation model data downscaled to a local and regional resolution to identify localized impacts. The Cal-Adapt tool makes predictions under two scenarios: RCP 4.5 – a low-emissions scenario, which assumes that emissions peak around 2040 and then decline, and RCP8.5 – a high-emissions scenario, which assumes that emissions continue to rise strongly through 2030 and plateau around 2100.

Below is a summary of the projected local effects of climate change on the City according to this 2020 CAP:
• Increased temperatures: Annual temperatures in the City are expected to rise steadily through the end of the century. The City’s historical average temperature, based on data from 1961–1990, is

56.4°F. Under the low-emissions scenario, the average annual temperature is projected to increase to

63.1°F between 2070 and 2099. The annual average temperature under the high-emissions scenario is projected to increase to 66.2°F between 2070 and 2099.
• More extreme heat days: Climate models project a significant rise in the number of extreme heat days. Historically, the City has experienced an average of four extreme heat days per year. Under the low-emissions scenario, the City is projected to experience 18 extreme heat days by 2060 and 32 extreme heat days by 2099. If GHG emissions continue to rise, the projected annual number of What is Climate Change?
Climate change refers to distinct changes in weather
conditions that result from increased atmospheric
greenhouse gas (GHG) emissions. Monthly mean GHG
levels now exceed 400 parts per million (ppm) for the
first time in recorded history. This GHG increase has
trapped heat in the atmosphere and is linked to an
increase in average global temperature and these
global temperature and GHG increases are resulting in
a series of changes to the global climate. These
changes include shifts in seasonal temperature
patterns; altered precipitation timing, amount, and
location; sea level rise due to melting glaciers and ice caps; ocean acidification due to increased carbon
dioxide (CO2) absorption; and altered wind and storm
event frequency and severity, including more frequent
and intense storms, droughts, and heat waves. Climate
change is not a discrete event, but a long-term hazard
that already affects communities in California.

Sources: NOAA 2017; IPCC 2018; SHMP 2018
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• More frequent heat waves: Heat waves, which are defined as four or more consecutive extreme heat days, have been historically infrequent in the City, averaging 0.4 heat wave per year from 1961 through 1990. Due to climate change, the number of heat waves is projected to rise significantly under both emissions scenarios. Under the low-emissions scenario, projections show an increase in the number of heat wave events, with two or three events per year at the middle of the century and seven events per year in 2099. The high-emissions scenario also shows an increase in the number of annual heat wave events, with between three and four heat wave events occurring annually by midcentury and as many as 10 heat wave events occurring annually by the end of the century. • Increased wildfire risk: Based on historical data from 1961–1990, El Dorado County experiences a decadal average loss of 3,362 hectares to wildfire. The probability that a wildfire will occur in any one year over a 10-year period, known as the decadal probability, is projected to increase through 2099, with the decadal probability of wildfire doubling by 2099 under the high-emissions scenario. Under the low-emissions scenario, the decadal average loss to wildfire is expected to increase to 4,050 hectares by mid-century and 5,073 hectares by 2099, a 50-percent increase. Under the high-emissions scenario, the decadal average loss to wildfire is projected to rise to 4,257 hectares by 2065 and more than double to 7,147 hectares by the end of the century. • More frequent extreme precipitation: The City experiences an average of six extreme precipitation events per year, based on historical data from 1961–1990. The City is expected to experience a 16.67- percent increase in extreme precipitation events by the end of the century under a low-emissions scenario. Under a high-emissions scenario, the City is projected to experience 50 percent more extreme precipitation events by 2099.
• More frequent flooding: As a result of these changes in temperature and precipitation patterns, local flooding hazards in the City are likely to increase over the coming century. The areas already subject to flood hazards will continue to experience flooding events, but these events will likely increase in frequency and severity, particularly in the winter months, as a larger percentage of areas within or near the City will experience annual precipitation falling as rain rather than snow. • Reduced snowpack: Spring snowpack is expected to decline throughout the central Sierra Nevada.

The City’s historical average snow water equivalent, a common measurement of snowpack, in April is

4.2 inches. Under the low-emissions pathway, the April snow water equivalent is expected to decrease by 67 percent by the end of the century, to 1.4 inches. Under the high-emissions pathway, the snow water equivalent is projected to be 0.6 inch, an 86-percent decrease, by 2099. 508
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Change and Health Profile Report mentions that in
addition to increasing temperatures and sea levels,
climate models also predict an increase in the frequency and intensity of extreme weather events such as floods
and droughts. Temperatures are expected to rise
substantially throughout this century. The wildfire risk for a significant portion of land within the County will also increase. Moreover, climate change can result in
direct and indirect impacts on human health and cause
socioeconomic disruption. For example, more frequent
extreme weather events would cause more fatal and
nonfatal injuries from drowning, being struck by objects, fire, explosions, electrocution, and/or exposure to toxic materials. Longer and more frequent droughts will also
worsen California’s existing lack of moisture, increasing the risk of wildfires, which would lead to damages to
properties, people, and infrastructure.

The California Tahoe Conservancy has partnered with several of the same federal, state, and local agencies and stakeholders, in addition to a team of technical experts to produce a set of climate adaptation plans.

The plan includes a scientific assessment of the vulnerability of Lake Tahoe, the forest system, and the communities in the Tahoe Basin to climate change, a primer of the major climate impacts, and a project portfolio that lists adaptation actions that partners are already undertaking to prepare for climate change.

The Integrated Vulnerability Assessment of Climate Change evaluates how patterns of temperature and precipitation will change at Lake Tahoe, and how these patterns will affect people, property, the economy, and the natural environment. The Tahoe Climate Adaptation Primer summarizes the key projected changes in temperature and shifts in precipitation in the Tahoe Basin based on the Integrated Vulnerability Assessment of Climate Change completed in 2020. While the City of South Lake Tahoe 2020 CAP focuses more on the impacts of climate change on the City, the projections in the Integrated Vulnerability Assessment are targeted towards the impacts on the Lake Tahoe Basin. Below are projections highlighted in the Integrated Vulnerability Assessment that add on to those in the City’s CAP:
• Precipitation at Lake level will shift: Precipitation will shift from being primarily snow to primarily rain due to warmer temperatures. Rising temperatures will also lead to more rain-on-snow events and earlier snowmelt.
• By the end of the century peak runoff in the Tahoe Basin will occur five months earlier: Peak runoff will occur earlier in the year because precipitation will fall more regularly as rain rather than snow, and flow into streams immediately, rather than accumulating as snowpack that slowly melts into the summer months.
• Deep water mixing in the Lake that occurs in the wintertime will be disrupted: Stronger thermal stratification with warm watering sitting on top of cooler water for longer periods will, in turn, expand the portions of the Lake that have low levels of dissolved oxygen (critical factor for aquatic life), increase the trapping of sediment and nutrients near the Lake surface, and promote algal blooms.

This will ultimately decrease the lake clarity.
• Lake level will rise during extreme precipitation events and exceed the operable range of the dam at Tahoe City one to two times every decade: The rising Lake level will cause steep slopes along the Lake Tahoe Sustainability Action Plan
The TRPA also initiated sustainability planning efforts in 2010 through a partnership of agencies and
organizations comprised of representatives from the
TRPA, Tahoe Metropolitan Planning Organization,
California Tahoe Conservancy, El Dorado County,
Placer County, City of South Lake Tahoe, North Lake
Tahoe Resort Association, and Sierra Nevada Alliance,
among numerous other members of the public.

The Sustainability Action Plan: A Sustainability Action Toolkit for Lake Tahoe (SAP) recognized sustainability
efforts already underway in the Tahoe Basin and
identified additional actions. It serves as a toolkit that agencies and local jurisdictions can use to develop
their sustainability actions under a consistent regional framework. It provides a pathway the region can
follow to achieve GHG emission reductions, prepare
for climate-readiness, promote resiliency planning,
foster a healthy community.

Source: TRPA 2013
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• Hydrologic patterns will shift and lead to long-term changes in ecosystem function: More annual precipitation that arrives as rain rather than snow will make the amount of water in the Tahoe Basin snowpack can hold decrease, and summertime streamflow will decline. Conversely, more intense storms, rain-on-snow events, and floods will lead to more runoff, and the corresponding increase in erosion, transportation of downstream pollutants, and potential damage to infrastructure. • Aquatic habitat will be impacted due to fluctuating lake levels and earlier peaks in runoff:

Native fish require cool streams in the summertime for spawning and under climate change scenarios, these streams will become warmer much earlier in the spring and summer, which will impact the ability of native species to reproduce.
• Bark beetle infestations will increase due to longer droughts and reduced soil moisture:

Drought conditions will lead to more insect outbreaks, bark beetle kills, and kill large numbers of aspen trees. Drought conditions will also reduce the size of meadows and increase the risk of wildfire.

Conifers may also supplant meadow habitats that lack consistent high groundwater levels.

The important consideration for hazard mitigation is that climate change is exacerbating the hazards which are already identified and profiled in this plan. The City and California are also already experiencing the impacts of climate change including prolonged drought, increased flooding due to shifts in peak runoff, increased average temperatures, shifts in the water cycle, and changes to precipitation patterns and the intensity of extreme events resulting from hazards, such as the Caldor Fire that started in August 2021 and affected South Lake Tahoe and the surrounding region. Climate change not only results in progressive changes, such as shifting weather patterns but also affects the frequency and severity of hazard events (SHMP 2018). Furthermore, climate change also generates an increase in the variance of climate patterns, and this increased variance creates challenges for hazards planning, which previously used historic recurrence rates to predict future events, and now must incorporate changes to the frequency, severity, and location due to climate change.

Risk assessment for hazards is built upon the frequency of past events and the assumption that historic occurrence rates are a good predictor of future event probability. With climate change, however, history is not an adequate predictor of the probability of future occurrences (SHMP 2018). Planning for climate change (and understanding the probability of future occurrences [see Section 4.3 below]) is therefore now based on understanding and integrating evolving climate change science and modeled projections that account for shifts in historic conditions due to climate change (SHMP 2018) into hazard mitigation planning.

Additional specifics associated with the hazards are discussed in the Climate Change Considerations subsection of each hazard profile. This section also summarizes whether climate change is anticipated to have a low, medium, or high influence on future hazards.

4.2 Asset Summary
As a starting point for analyzing the Planning Area’s vulnerability to identified hazards, the HMPC used a variety of data, including data provided by El Dorado County (e.g. structure values, assessor data) to define a baseline against which all disaster impacts could be compared. If a catastrophic disaster were to occur in the Planning Area, this section describes significant assets exposed or at risk in the Planning Area.

Data used in this baseline assessment included:
• Total assets at risk;
• Critical facility inventory;
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• Population statistics, land use, and growth/development trends.

4.2.1 Total Assets at Risk
A spatial parcel dataset containing attributes such as structure values and year of property construction was provided by the City of South Lake Tahoe GIS Department, alongside a building outline layer useful in counting buildings per parcel. Property type, valuation details, and other information contained in this plan are based on 2021 data from the El Dorado County Assessor’s Office. This data provided the baseline for an inventory of the total exposure of developed properties within the City of South Lake Tahoe. This data helps to ensure that the LHMP can be updated over time to reflect changes in development. It is important to note that depending on the nature and type of hazard event or disaster, it is generally the value of the infrastructure or improvements to the parcels that are of concern or at risk. Generally, the land itself is not a total loss but may result in a reduction in value. Thus, the parcel analysis excludes land value.

Once the dataset was reviewed and organized, the parcel layer was clipped to the boundaries of the City of South Lake Tahoe City limits (and in some instances the SOI boundary). For the purpose of parcel analysis and exposure calculations only parcels with improved values were used, except for exempt or government properties (which may not include an improvement value per its categorization and is one limitation that results in the total improvement values underestimating the actual value). “Improved” parcels have an improvement value greater than zero. Contents values were also estimated, as a percentage of building value based on their property type, using FEMA/Hazus guidelines. Content value estimates are based on 100 percent of the structure value for commercial structures, 150 percent of the structure value for industrial structures, and finally 50 percent for residential structures. Improvement values were added to contents values to calculate the total structure values for all properties in the parcel layer. The parcel layer, originally in the form of polygons, was then converted into points based on the center (or centroid) of a parcel to then be used in overlay analysis with those hazards profiled in this plan that are available in spatial format (i.e. flood and fire). These outputs summarize the count and value of improved properties, contents, and total values for the property inventory, and the exposure values by property type for the City of South Lake Tahoe. Table 4-4 summarizes the total improved parcel exposure by parcel type for the City of South Lake Tahoe.

Table 4-4 Total Improved Parcel Exposure by Property Type Parcel Type Total
Parcels
Improved Value Content Value Total Exposure
Value
Commercial 440 $575,653,684 $575,653,684 $1,151,307,368 Exempt 20 $0 $0 $0
Industrial 206 $176,406,700 $264,610,050 $441,016,750
Miscellaneous 41 $60,740,923 $60,740,923 $121,481,846
Residential 11,050 $2,916,247,586 $1,458,123,793 $4,374,371,379 Total 11,757 $3,729,048,893 $2,359,128,450 $6,088,177,343 Source: Wood analysis based on City of South Lake Tahoe and El Dorado County Assessor’s Office Data 2021 Critical Facility and Community Lifeline Inventory
A critical facility is one that is essential in providing utility or direction either during the response to an emergency or during the recovery operation. The critical facilities and lifelines GIS database was based on a combination of City-provided data, stakeholder input, critical facility datasets provided by several of the water and wastewater purveyors in the City, Homeland Infrastructure Foundation-Level Data (HIFLD), and 511
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The City and the HMPC were able to Review the map-based critical facility data and tabular formats to ensure all facilities were included before the assessment was conducted. The outcome was a robust and detailed dataset that includes over 190 critical facilities. The results are summarized here and provide the basis for GIS-based vulnerability analyses, where data permitted.

Lifeline categories are FEMA’s recommended way to standardize the classification of critical facilities and infrastructure which provide indispensable service, operation, or function to a community. A lifeline is defined as providing indispensable service that enables the continuous operation of critical business and government functions and is critical to human health and safety, or economic security. FEMA sorts critical facilities into seven lifeline categories as shown in Figure 4-1.

Figure 4-1 Community Lifeline Categories
Source: FEMA 2021
These categorizations are particularly useful as they:
• Enable effort consolidations between government and other organizations (e.g., infrastructure owners and operators).
• Enable integration of preparedness efforts among plans, easier identification of unmet critical facility needs.
• Refine sources and products to enhance awareness, capability gaps, and progress towards stabilization.
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• Highlight lifeline-related priority areas regarding general operations as well as response efforts.

Table 4-5 shows a summary of the critical facilities evaluated in the City’s vulnerability assessment. Figure 4-2 illustrates the location of each critical facility. Please note given the sensitivity of certain water resources, potable water facilities are not displayed on the map, but they were included in the analysis.

Table 4-5 Summary of South Lake Tahoe Critical Facilities by Lifeline FEMA Lifeline Facility Type Count Total
Communications Radio Tower 6 13
Cell Tower 1
FM Trans Tower 3
Land Mobile Private Transmission Tower 3
Energy Equipment Storage 1 2
Substation 1
Food, Water, Shelter Community Shelter 9 102
Pump Station 41
Well 19
Lift Station 2
Main Station 1
WWTP 2
Booster Station 15
Water Tank 13
Hazardous Material Refuse Transfer Station 1 2
Wastewater Treatment Facility 1
Health and Medical Senior Center 1 7
Assisted Living Residence/Nursing Home 1
Urgent Care 2
Heliport 2
Hospital 1
Safety and Security Fire Station/Fire Training Park 8 50 Police Station 3
City Facility 13
Human Services 1
Airport/Landing Site 3
Childcare Facility 13
Elementary School 4
Middle School 1
High School 1
Continuing Education Center/Boys & Girls Club 2
College 1
Transportation Airport 1 19
Bus Transit Station 4
Gondola Transit Station 1
Boat Ramp 1
Good Condition Bridge 9
Fair Condition Bridge 3
Grand Total 195
Sources: City of South Lake Tahoe 2021; HIFLD 2021; Wood Analysis of City and HIFLD datasets 513
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Assessing the City of South Lake Tahoe’s vulnerability to disaster also involves inventorying the natural, historical, and cultural assets of the area. This step is important for the following reasons:
• The community may decide that these types of resources warrant a greater degree of protection due to their unique and irreplaceable nature and contribution to the overall economy. • In the event of a disaster, an accurate inventory of natural, historical and cultural resources allows for more prudent care in the disaster’s immediate aftermath when the potential for additional impacts is higher.
• The rules for reconstruction, restoration, rehabilitation, and/or replacement are often different for these types of designated resources.
• Natural resources can have beneficial functions that reduce the impacts of natural hazards, for example, wetlands and riparian habitat which help absorb and attenuate floodwaters and thus support overall mitigation objectives.

Cultural Resources
Historical resources are buildings, structures, objects, places, and areas that are eligible for listing in the National Register of Historic Places (NRHP), the California Register of Historic Resources (CRHR), or the City’s List of Historic Resources, have an association with important persons, events in history, or cultural heritage, or have distinctive design or construction method.

For purpose of federal actions, a qualified historic resource is defined as a property listed in or formally determined eligible for listing in the NRHP before a disaster occurs. The NRHP is part of a national program to coordinate and support public and private efforts to identify, evaluate, and protect historic and archaeological resources. Properties listed include districts (i.e. South Lake Tahoe Historic Commercial District), sites, buildings, structures, and objects that are significant in American history, architecture, archaeology, engineering, and culture. The National Register is administered by the U.S. Department of the Interior National Park Service. Local and state agencies may consider a broader definition of qualified historic properties in the review, evaluation, and treatment of properties damaged during a disaster.

The State of California Office of Historic Preservation can provide technical rehabilitation and preservation services for historic properties affected by a natural disaster. Depending on the hazard, protection could range from emergency preparedness, developing a fire safe zone around sites susceptible to wildfires, or seismically strengthening or structurally reinforcing structures.

State and local registers of historic resources provide designated Historical Landmarks, Points of Historical Interest, and Historic Buildings. These resources include, but are not limited to:
• The California Register of Historical Resources (CRHR) • The California Historical Landmarks
• The California Inventory of Historical Resources
• The California Points of Historical Interest
Table 4-6 summarizes the historic and cultural resources found in the National and California Register of Historic Places for the South Lake Tahoe area.
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Historical Resource
Name
Listed Date Location Other Names or Description
Baldwin Estate 4/1/1987 NW of US 50 and CA 89 jct.
on N side of CA 89
Tallac Historic Site (together
with Pope Estate)
Heller Estate 4/1/1987 NW of US 50 and CA 89 jct.
on N side of CA 89
Valhalla Grand Hall
Newhall Estate
Entrance Pillars
5/9/1994 NA NA
Pope Estate 4/1/1987 NW of US 50 and CA 89 jct.
on N side of CA 89
Tallac Historic Site (together
with Baldwin Estate)
Site of Echo Summit 12/2/2013 21200 Highway 50 Training site for American track and field athletes preparing to
go to the 1968 Olympics in
Mexico City; significant for its
association with sports history
and civil rights history
Tahoe Meadows 3/29/1990 US 50 between Ski Run
Blvd. and Park Ave.

N/A
Vikingsholm 10/10/1996 10001 Emerald Bay Rd. A 38-room mansion on the shore of Emerald Bay at Lake
Tahoe
Source: NRHP, 2021
Lists of designated historical resources change periodically, and they may not include those currently in the nomination process and not yet listed. Additionally, as defined by the National Environmental Policy Act (NEPA), any property over 50 years of age is considered a historic resource and is potentially eligible for listing on the National Register. Thus, in the event that the property is to be altered, or has been altered, as the result of a major federal action, the property must be evaluated under the guidelines set forth by NEPA. Structural mitigation projects are considered alterations for the purpose of this regulation.

Cultural resources defined in California Environmental Quality Act (CEQA) Section 15064.5 include prehistoric and historic archaeological resources; historic-period resources (buildings, structures, area, place, or objects). Archaeological resources reflect past human activity extending from Native American prehistoric cultures throughout the early 20th century. The artifacts left by previous occupants may be encountered in small to large residential sites, or special use areas.

Many cultural and historical resources in the City are vulnerable to several hazards due to location and the nature of their construction. Some of these risks include earthquakes, wildfires, floods, or severe weather.

Tribal Cultural Resources
Tribal cultural resources are defined in Public Resources Code (PRC) Section 21074.1 as a site, feature, place, cultural landscape that is geographically defined in terms of the size and scope of the landscape, sacred place, or object with cultural value to a California Native American tribe. A Native American tribe is defined as “a federally recognized California Native American tribe or a non-federally recognized California Native American tribe that is on the contact list maintained by the Native American Heritage Commission”. Traditional tribal cultural places are defined in PRC Sections 5097.9 and 5097.993 to include sanctified cemeteries, places of worship, religious or ceremonial sites, or sacred shrines, or any historic, cultural, or sacred site that is listed on or eligible for the CRHR including any historic or prehistoric ruins, burial grounds, or archaeological site. Cultural and tribal resources are governed primarily by federal, 516
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• Assembly Bill 52 (PRC Section 21080.3.1) mandates early tribal consultation prior to and during CEQA review to consider tribal cultural values in the determination of project impacts and mitigation. • Senate Bill 18 (Government Code 655352.3) requires cities and counties to consult with Native American tribes early during broad land use planning efforts on both public and private lands, prior to the site- and project-specific land use decisions. Consultation is intended to encourage preservation and protection of traditional tribal cultural places by developing treatment and management plans that might include incorporating the cultural places into designated open spaces. • State Executive Order B-10-11 (2011) established the Governor’s Tribal Advisor position and established Administration Policy to encourage State Agencies to communicate and consult with Californian tribes regarding tribal cultural resources.

Natural Resources
The City of South Lake Tahoe contains diverse natural resources, exemplified by the fact that the City resides in the Sierra Nevada mountains and Lake Tahoe abutting the City from the north.

Natural resources are important to include in benefit/cost analyses for future projects and may be used to leverage additional funding for mitigation projects that also contribute to community goals for protecting sensitive natural resources. Inventory and awareness of natural resource assets are vital to meeting conservation objectives. Natural resources also exhibit varying levels of resiliency to anthropogenic impacts, climate change, and natural hazards such as flooding, drought, or wildfire.

Special Status Species
To further understand natural resources that may be particularly vulnerable to a hazard event, as well as those that need consideration when implementing mitigation activities, it is important to identify at-risk species (endangered and threatened species) potentially located in the City of South Lake Tahoe and its Planning Area. The United States Fish and Wildlife Service (USFWS) maintains a list of federally-listed threatened and endangered species for the country, which can be queried at the State and County levels.

The California Department of Fish and Wildlife (CDFW) also maintains species lists and accounts for threatened and endangered species. State and federal laws protect the habitat of these species through the environmental review process. Species of special concern may additionally include species that meet the State definition of threatened or endangered but have not been formally listed, experience seriously population declines or habitat decline, or have naturally small populations exhibiting high susceptibility to population decline (CDFW 2019). Table 4-7 summarizes those special status species as indicated in the USFWS database that are located in El Dorado County and likely the areas surrounding the City of South Lake Tahoe Planning Area.

Table 4-7 Threatened and Endangered Species in El Dorado County and City of South Lake Tahoe
Common Name Scientific Name Group Status
California red-legged frog Rana draytonii Amphibians Threatened California tiger Salamander Ambystoma californiense Amphibians Endangered Conservancy fairy shrimp Branchinecta conservatio Crustaceans Endangered Cui-ui Chasmistes cujus Fishes Endangered
El Dorado bedstraw Galium californicum ssp. sierrae Flowering Plants Endangered Giant garter snake Thamnophis gigas Reptiles Threatened Greater sage-grouse Centrocercus urophasianus Birds Resolved Taxon Lahontan cutthroat trout Oncorhynchus clarkii henshawi Fishes Threatened Layne's butterweed Senecio layneae Flowering Plants Threatened 517
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longfin smelt Spirinchus thaleichthys Fishes Candidate
monarch butterfly Danaus plexippus Insects Candidate
North American wolverine Gulo luscus Mammals Resolved Taxon Pine Hill ceanothus Ceanothus roderickii Flowering Plants Endangered Pine Hill flannelbush Fremontodendron californicum ssp. decumbens
Flowering Plants Endangered
Sacramento Orcutt grass Orcuttia viscida Flowering Plants Endangered Sierra Nevada yellow-legged
frog
Rana sierrae Amphibians Endangered
Stebbins' morning-glory Calystegia stebbinsii Flowering Plants Endangered Tahoe yellow cress Rorippa subumbellata Flowering Plants Resolved Taxon Valley elderberry longhorn
beetle
Desmocerus californicus dimorphus Insects Threatened
Vernal pool fairy shrimp Branchinecta lynchi Crustaceans Threatened Vernal pool tadpole shrimp Lepidurus packardi Crustaceans Endangered Whitebark pine Pinus albicaulis Conifers and Cycads Proposed Threatened Yellow-billed Cuckoo Coccyzus americanus Birds Threatened Yosemite toad Anaxyrus canorus Amphibians Threatened
Source: USFWS – Environmental Conservation Online System, 2021 Population, Growth, and Development Trends
Between 2010 and 2019 the population of South Lake Tahoe increased by 1,485 persons (6.9 percent) (US Census 2021). During the same time, the state of California's population increased by 6 percent and El Dorado County’s population increased by 6.4 percent. This growth trend demonstrates that the City of South Lake Tahoe has grown slightly faster than the State and the surrounding region (US Census 2021).

The City’s annual population growth rate is currently at around 0.8%. (California Demographic Data: State Dept. of Finance), outpacing the State and nation’s current population growth rate (around 0.38% and

0.5% respectively).

As discussed in Chapter 2, the City of South Lake Tahoe is located in a unique regulatory and planning environment – the Lake Tahoe Region. TRPA has land use and environmental regulatory authority for the long‐term preservation of Lake Tahoe and its environments. The City acknowledges the role of TRPA to adopt environmental thresholds regulating carrying capacities and a Regional Plan to achieve the goal of the long‐term preservation of Lake Tahoe. According to the City’s 2011 General Plan’s Land Use and Community Design Element, the City will pursue the maximum amount of available CFA that can be allocated by the TRPA as an incentive for revitalization, economic growth, and urban renewal. In terms of future residential development, the City intends to pursue the maximum amount of available residential unit allocations use them as an incentive for revitalization, including workforce housing. In summary, the City encourages ways to maximize their ability to secure development rights from TRPA, including promoting infill development and revitalization as well as the reuse and expansion of existing and vacant sites in the City. Nevertheless, as previously mentioned, one of TRPA’s main tools for protecting the environment is growth control regulations, which limit the amount of growth and development that occurs in the Basin each year.

Additional information on population and growth and development trends are in Section 2.4 and Section

2.8 in Chapter 2.
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4.3 Hazard Profiles and Risk Assessment
Requirement §201.6(c)(2)(i): [The risk assessment shall include a] description of the location and extent of all natural hazards that can affect the jurisdiction. The plan shall include information on previous occurrences of hazard events and on the probability of future hazard events.

Requirement §201.6(c)(2)(ii): [The risk assessment shall include a] description of the jurisdiction’s vulnerability to the hazards described in paragraph (c)(2)(i) of this section. This description shall include an overall summary of each hazard and its impact on the community.

Requirement §201.6(c)(2)(ii)(A): The plan should describe vulnerability in terms of the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the identified hazard areas.

Requirement §201.6(c)(2)(ii)(B): [The plan should describe vulnerability in terms of an] estimate of the potential dollar losses to vulnerable structures identified in paragraph (c)(2)(i)(A) of this section and a description of the methodology used to prepare the estimate.

Requirement §201.6(c)(2)(ii)(C): [The plan should describe vulnerability in terms of] providing a general description of land uses and development trends within the community so that mitigation options can be considered in future land use decisions.

The hazards identified in Section 4.1 Hazard Identification: Natural Hazards are profiled individually in this section. In general, the information provided by HMPC is integrated into this section with information from other data sources. These profiles set the stage for the vulnerability assessment for each natural hazard that follows the detailed hazard profiles.

Each hazard is profiled in the following format:
• Hazard Description - This section gives a description of the hazard and associated issues followed by details on the hazard that are specific to the City of South Lake Tahoe Planning Area. • Location – This section provides a spatial description of the potential locations or geographic areas in the City of South Lake Tahoe of where the hazard is expected to impact. • Extent (Magnitude/Severity) - This section describes the potential strength or magnitude of the hazard as it pertains to the City of South Lake Tahoe. Different hazards may have different measures of extent.
• Previous Occurrences - This section contains information on historical incidents, including impacts where known. The extent or location of the hazard within or near the Planning Area is also included in this subsection. Historical incident worksheets and other data sources were used to capture information on past occurrences.
• Probability of Future Occurrence - The frequency of past events is used in this section to gauge the likelihood of future occurrences. Where possible, frequency was calculated based on existing data.

Frequency was determined by dividing the number of events observed by the number of years on record and multiplying by 100. This gives the percent chance of an event happening in any given year (e.g., three droughts over a 30-year period equates to a 10 percent chance of a drought in any given year). The likelihood of future occurrences is categorized into one of the following classifications:
- Highly Likely - Nearly 100 percent chance of occurrence in next year or happens every year. - Likely - Between 10 and 99 percent chance of occurrence in next year or has a recurrence interval of 10 years or less.
- Occasional - Between 1 and 10 percent chance of occurrence in the next year or has a recurrence interval of 11 to 100 years.
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The risk assessment for most hazards is built upon the frequency of past events and the assumption that historic occurrence rates are a good predictor of future event probability. With climate change; however, history is not an adequate predictor of the probability of future occurrences (SHMP 2018). Planning for climate change is based on understanding and integrating evolving climate change science and modeled projections that account for shifts in historic conditions due to climate change into hazard mitigation planning (SHMP 2018). For these reasons, the likelihood of future occurrences for climate change and sea level rise impacts is categorized into one of the four classifications, but this classification is based on climate change science and modeled projections.
• Climate Change Considerations – Climate change refers to a long-term change in the earth’s temperature, precipitation, humidity, and seasons. This section addresses the probable effects of climate change qualitatively and as a secondary impact for each identified hazard. In other words, it describes the potential for climate change to affect the frequency and severity of natural hazards.

Impacts can include water supply shortages, changes in the frequency, intensity, and extent of drought and extreme heat events, more precipitation and flooding risks, and increasing temperatures.

This section also concludes whether climate change is anticipated to have a low, medium, or high influence on future hazard impacts.

The discussion relies on information from the Fifth Assessment Report from the Intergovernmental Panel on Climate Change (IPCC) Climate Change 2013: The Physical Science Basis Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC 2018). It also relies on numerous California publications on climate change and climate adaptation including:
• California’s Fourth Climate Assessment (California Natural Resources Agency 2018a); • Safeguarding California Plan: 2018 Update – California’s Climate Adaptation Strategy (Cal-Adapt 2018);
• 2014 Safeguarding California: Reducing Climate Risk (California Natural Resources Agency 2014); and • 2009 California Climate Adaptation Strategy (CAS) (California Natural Resources Agency 2009).

The discussion integrates climate information from Cal-Adapt, a website that gathers data on how climate change might affect California at the local level based on the State’s scientific and research community (CEC 2018). The climate change considerations subsections also summarize climate change modeling and findings from the City of South Lake Tahoe CAP and the Lake Tahoe Integrated Climate Vulnerability Assessment. Climate change is addressed in the plan as a secondary impact for each hazard.

Vulnerability Assessment – The vulnerability of the Planning Area to a specific natural hazard is assessed through the study of potential impacts to specific sectors:
• Property
• People
• Economy
• Critical Facilities and Infrastructure
• Historic, Cultural, and Natural Resources
• Future Development
Risk Summary – This is a summary of key findings and risks based on threat, vulnerability and consequences to the Planning Area from the specific hazard.

The significance of each hazard was determined based on the hazard profile, focusing on key criteria such as frequency and resulting damage, including deaths/injuries, and property and economic damage. This 520
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4.3.1 Avalanches
Hazard Description
An avalanche is a fall, release, or slide of a mass of snow in an amount sufficient enough to cause damage to or threaten the safety of people. Avalanches are possible when weak layers of snow within the cumulative seasonal snowpack fail to support the weight of the snow above and collapse. The result causes the overlying snow to break free and flow downhill. There are two destructive elements at work within an avalanche. Primarily, the actual impact from the displaced snow and ice is a concern. Embedded within the snow, debris such as broken-off trees and branches and rocks are just as dangerous as the snow itself. Secondly, the avalanche wind, caused by air pushed ahead of the moving mass of snow, can cause damage as well.

Terrain most susceptible to avalanches is typically in sheltered regions of the mountain topography where snow is most prone to accumulate and along steep slope angles ranging from 30 to 45 degrees. The most sheltered aspects in the Sierra Nevada, where snow can most greatly accumulate, are upon north and northeast facing slopes. These slope faces must also be situated above 7,000 feet where snow is more likely to accumulate throughout the winter snowfall season, which typically lasts from November through April in El Dorado County.

Snow avalanches can release loose or slabslides and can be classified as wet or dry events, depending on the moisture content of the snowpack. Loss avalanches involve snow near the surface and release when cohesion is lost between the snow grains. Slab avalanches extend into deeper snow and release cohesiveness when a lower and weaker layer of snow fails. Slab avalanches can be both wet or dry and extremely large and destructive. Both types can also flow downhill for long distances on gentle terrain and often damage or destroy buildings, cabins, and electrical transmission lines.

Avalanches can be triggered by human activity or environmental factors, such as wind loading, precipitation, or warm weather. Human-caused avalanches around the City usually occur away from developed areas, and most incidents involve backcountry skiers and hikers. Because human-triggered avalanche events are typically far from developed areas, they cause less damage and loss of life than a naturally-caused avalanche could cause that occurs near developed areas. Once triggered, an avalanche path consists of a starting zone where they begin, a track where they develop speed and velocity, and a runout zone at lower gradient slopes where the slides slow down and the debris zone forms.

Location
Extensive – The City is located in a basin surrounded by the mountain peaks of the Sierra Nevada mountain range, a tilted fault block geologic formation that forms steep mountain slopes across the eastern portion of California. The City's elevation ranges from about 6,200 feet to more than 7,440 feet, which results in a high-relief topography. Given these elevation characteristics, combined with climatic factors, all areas of the City are susceptible to winter storms and heavy snow and snow avalanches throughout the winter months. Areas most susceptible to avalanches are located along the southern edge of the City, where there are known avalanche runout areas near Heavenly Mountain Resort and the background areas around the resort. According to El Dorado County’s 2018 LHMP, avalanche hazards exist in eastern El Dorado County. The Sierra Avalanche Center designated an Avalanche Zone in 2018 521
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Limited – Avalanches are isolated occurrences predominantly located in the backcountry areas of the City and its surrounding areas. Avalanche events would most likely affect individuals in the backcountry during the snow seasons. Avalanche danger within the established ski resorts as well as on the highways that traverse the high elevation passes in El Dorado County is of a lesser degree given that safety measures are in place.

Weather and terrain factors determine avalanche severity and danger:
• Weather:
- Storms – A large percentage of all snow avalanches occur during and shortly after storms. - Rate of snowfall – Snow falling at a rate of 1 inch or more per hour rapidly increases avalanche danger.
- Temperature – Storms starting with low temperatures and dry snow, followed by rising temperatures and wetter snow, are more likely to cause avalanches than storms that start warm and then cool with snowfall.
- Wet snow – Rainstorms or spring weather with warm, moist winds and cloudy nights can warm the snow cover, resulting in wet snow avalanches. Wet snow avalanches are more likely on sunexposed terrain (south-facing slopes) and under exposed rocks or cliffs. • Terrain:
- Ground cover – Large rocks, trees, and heavy shrubs help anchor snow. - Slope profile – Dangerous slab avalanches are more likely to occur on convex slopes. - Slope aspect – Leeward slopes are dangerous because windblown snow adds depth and creates dense slabs. South-facing slopes are more dangerous in the springtime. - Slope steepness – Snow avalanches are most common on slopes of 30 to 45 degrees.

The common factors contributing to the avalanche hazard are existing snow depth, existing snow surface, new snow depth, new snow type, density, snowfall intensity, precipitation intensity, settlement, wind direction and speed, temperature, and subsurface snow crystal structure. The danger of an avalanche can be described in terms of its likelihood, size, which includes its width, length it travels, or the depth of the debris, and distribution. While there are a few scales that rate avalanches based on their destructive force, such as the D-Scale, a commonly used scale for search and rescue, ski patrollers, and backcountry travelers measures avalanche severity based on size, the mass, length, and pressure of the slide. Table 4-8 summarizes this avalanche danger scale.

Table 4-8 Avalanche Danger Scale
Danger Level Travel Advice Likelihood of Avalanches Avalanche Size and Distribution 5 – Extreme Avoid all avalanche
terrain.

Natural and humantriggered avalanches
certain.

Large to very large avalanches in
many areas.
4 – High Very dangerous
avalanche conditions.

Travel in avalanche
terrain not
recommended.

Natural avalanches likely;
human-triggered
avalanches very likely.

Large avalanches in many areas; or
very large avalanches in specific
area.
3 – Considerable Dangerous avalanche
conditions. Careful
snowpack evaluation,
cautious route-finding
Natural avalanches
possible; human-triggered
avalanches likely.

Small avalanches in many areas; or
large avalanches in specific areas;
or very large avalanches in isolated
area.
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decision-making
essential.
2 – Moderate Heightened avalanche
conditions on specific
terrain features. Evaluate
snow and terrain
carefully; identify
features of concern.

Natural avalanches unlikely;
human-triggered
avalanches possible.

Small avalanches in specific areas;
or large avalanches in isolated
areas.
1 – Low Generally safe avalanche
conditions. Watch for
unstable snow on
isolated terrain features.

Natural and humantriggered avalanches
unlikely.

Small avalanches in isolated areas
or extreme terrain.

Source: Sierra Avalanche Center 2021.

The effects of an avalanche are confined to the areas within and around the avalanche path. Nowadays in the City, the areas of substantial avalanche danger are known and usually avoided. Avalanche areas in Heavenly Mountain Resort and along the City's state highways are carefully managed to drastically reduce the chance for avalanche-causing conditions to develop. Therefore, few unplanned or damage-causing avalanches occur in places where people or property might be threatened. However, avalanches can and do still happen within the City’s Planning Area. Although personal injury or property damage is unlikely, these events are a possibility.

The avalanche season extends from the first major snowfalls of late fall to whenever the last remnants of snow have melted away. In some of the highest elevation areas around the City, it may be possible during some years for snow to remain the entire year.

The greatest impact that avalanches have on the City is on transportation infrastructure. Two state highways pass through the City – Highway 50 and Highway 89. Highway 50 over Echo Pass is closed intermittently during the winter months, in part because of avalanche danger and for the management of avalanche control centers (i.e., triggering systems) by the California Department of Transportation (Caltrans). This closure limits the travel options of the City’s residents and places increased importance on Highway 89 over Luther Pass and on Nevada State Route 207 over the 7,334-foot Daggett Pass, which is maintained as a year-round highway. Highway 50, then, is the City's only east to west travel corridor during the winter months. During winter storms, periodic avalanche control must be performed on the highway to promote motorist safety over the passes. Without these avalanche control measures being performed by Caltrans, traveling over the County's main highway corridors would be difficult during the winter season. With avalanche control, public safety is improved, and avalanche danger is minimized.

Safety precaution is also in place to guarantee the safety and wellness of residents and tourists during snow seasons. For example, the major ski resort in the City – Heavenly Mountain Resort employs avalanche control techniques to mitigate avalanche danger. Ski patrollers perform avalanche control every morning, which is required to promote safety throughout the mountain for all skiers and riders. Much of the dangers associated with avalanches are known and efforts are made to lessen the potential for avalanche events in areas frequented by people.

However, problems can arise in backcountry areas where avalanche control measures are not in place.

Here, out-of-bounds downhill skiers, cross country skiers, and snowmobile riders can trigger avalanches.

Thus, avalanches can still pose a threat to life and property. The City is still vulnerable to avalanche danger in areas that are underdeveloped and/or lack avalanche control methods. If individuals travel into backcountry regions during the snow seasons, injuries will still be a possibility. 525
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Previous Occurrences
Since 1950, there have been 18 avalanches that resulted in nine deaths and 12 injuries in El Dorado County (NOAA’s National Centers for Environmental Information). It is assumed that heavy snow hazard events across El Dorado County are likely to have also affected the City of South Lake Tahoe at some point or to some extent.

Sierra Avalanche Center functions as a private-public partnership between the US Forest Service and a 501(c)(3) not for profit organization known as Sierra Avalanche Center (SAC). SAC's mission is to inform and educate the public about backcountry avalanche conditions in the greater Lake Tahoe area. SAC makes avalanche forecasts regularly on their website and South Lake Tahoe is included in their forecasting zone. SAC also keeps records of snow conditions, avalanche observations, and incidents that are from a variety of professional sources, mountain guides, and the general public. SAC also keeps records of the most recent 15 observations at a time, and this spatial data provides a good indication of recent snow conditions and avalanche activity for an area (SAC 2021).

There have not been any recorded occurrences of avalanches within the City of South Lake Tahoe, however, a few incidents happened in the vicinity of the City in recent years. Figure 4-4 is a screenshot from the SAC’s interactive map application that shows the recent incidents that happened in the area.

These three events, from north to south and west to east, occurred on April 8, 2020, February 14, 2021, and February 13, 2021, respectively.
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Probability of Future Occurrences
Highly Likely – Terrain and climatic factors make the City easily susceptible to avalanche hazards, which can be prevalent during snow seasons and impose a potential danger on individuals who venture into the backcountry regions near the City. Given the City’s proximity to steep terrain and because backcountry avalanches triggered by human activity are an annual occurrence in El Dorado County, the City can be affected, but these hazards are not expected to threaten residents and property. Potentially destructive avalanches triggered by environmental conditions are less common but can occur in higher hazard areas with steeper terrain.
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The likelihood and nature of future avalanches may be affected by climate change. Winters are becoming shorter, which means there is potential for weaker snow accumulations at the very bottom of the snowpack. As more snow piles on top of the weak layer, and temperatures remain warm, the upper, moisture-laden layers became vulnerable to sliding. More extreme precipitation events that deposit large amounts of snow in a short period, as well as increased temperatures, could also periodically increase the potential for large avalanches.

Vulnerability Assessment
Property
Building impacts are negligible. Any damage is likely to be insignificant or limited to snow sliding from building roofs. Heavenly Mountain Resort does not contain residential structures but does contain commercial properties and infrastructure, such as lodges, ski lifts that can be at risk from runout paths from the ski area.

People
Backcountry recreationists and road crews are the most at risk of avalanche dangers. Rising numbers of outdoor enthusiasts may lead to an increase in fatal avalanche occurrences. Beyond backcountry skiing, there has been a growing interest in other forms of recreation, and an introduction of new toys that are bigger, heavier, and intensify avalanche susceptibility. There is no effective way to keep the public out of avalanche-prone recreational areas, even during times of highest risk. Backcountry avalanche incidents involve search and rescue teams and resources, which can put the personnel at risk. The key actions to limiting impacts to individuals recreating in hazardous areas include spreading knowledge and awareness of the hazard and being properly equipped for self-rescue, if necessary, with tools such as locater beacons, shovels, GPS units and other communication tools and probes. Hundreds of visitors may also be on the slopes at Heavenly Mountain Resort at any given time, but avalanche risk at ski resorts is well managed, which greatly reduces the risk to the general public and visitors.

Critical Facilities and Infrastructure
Avalanches can cause several types of secondary effects, such as blocking roads, which can isolate residents and businesses and delay commercial, public, and private transportation. Other potential problems resulting from avalanches are power and communication failures. It is unlikely that there are critical facilities exposed to avalanche hazards, although there may be some facilities, in particular, the possibility of disruption to the electrical grid network. Other potential problems resulting from avalanches are power and communication failures. Highway 50 and Highway 89 are prone to receive the impact from avalanche hazards during winter months, but avalanche control measures are in place to ensure the safety of motorists.

Economy
Avalanche activity inside or outside the City and its surrounding areas can disrupt transportation into and out from the local communities, which could result in temporary economic impacts. Closures of transportation routes could prevent the import and export of goods and services, as well as disrupt the tourism and recreation industry.
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Avalanches are a natural event, but they can negatively affect the environment, including trees located on steep slopes. A large avalanche can knock down many trees and kill the wildlife that lives in and under them. In spring, this loss of vegetation on the mountains may weaken the soil, causing landslides and mudflows. If significant woody debris reaches the valley bottoms, it could also cause a potential for ponding and flooding.

The impact on historic or cultural resources in the City should be negligible, which is similar to avalanche hazard’s potential impact on properties. However, the exact damage should be evaluated on a case-bycase basis, for example, worn-out structures are more prone to potential damage from avalanche and heavy snow hazards.

Development Trends
Development and population growth in the City are slowly increasing. As tourism and backcountry recreation increase and more travelers visit the City, there could be increased exposure to avalanche risks.

However, as mentioned above, the City and relevant agencies have taken precautionary measures to guarantee public safety. The City’s 2011 General Plan Health and Safety Element lists “to protect and maintain the safety of residents, businesses, and visitors by reducing the threat of avalanches” as its goal regarding addressing avalanche hazards. The City will continue to identify avalanche hazard areas and enforce special standards for construction in avalanche hazard areas. The City will also continue disallowing the construction of new buildings or large-scale public gathering spaces in avalanche hazard areas.

Risk Summary
• Since 1950, there have been 18 avalanches that resulted in nine deaths and 12 injuries in El Dorado County.
• Backcountry recreationists, road crews, and motorists along are the most at risk of avalanche dangers. • Avalanches tend to happen in the backcountry areas of the City and its surrounding areas; avalanche events would most likely affect individuals in the backcountry during the snow seasons; avalanches could also happen within ski resorts as well as on the highways. Precautionary safety measures such as avalanche control and forecasts are in place to maximize the protection to the public. • There could be increased exposure to avalanche risks given the increase in tourism and as backcountry recreation increases; the City is acting proactively to minimize the potential danger by further identifying avalanche hazard areas and forbidding the construction of buildings of any kind within avalanche hazard areas.
• To further limit impacts to individuals, spreading knowledge and awareness of the hazard and being properly equipped for self-rescue are critical.
• The overall significance of avalanches in the City is Low.

4.3.2 Dam Incidents
Hazard Description
Dams are manmade structures built for a variety of uses, including flood protection, power generation, agriculture, water supply, and recreation. When dams are constructed for flood protection, they usually are engineered to withstand a flood with a computed risk of occurrence. For example, a dam may be designed to contain a flood at a location on a stream that has a certain probability of occurring in any one year. If prolonged periods of rainfall and flooding occur that exceed the design requirements, that 529
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• Earthquake
• Inadequate spillway capacity resulting in excess overtopping flows • Internal erosion caused by embankment or foundation leakage or piping or rodent activity • Improper design
• Improper maintenance
• Negligent operation
• Failure of upstream dams on the same waterway
Water released by a failed dam generates tremendous energy and can cause a flood that is catastrophic to life and property. A catastrophic dam incident or failure could challenge local response capabilities and require evacuations to save lives. Impacts on life safety will depend on the warning time and the resources available to notify and evacuate the public. Major loss of life could result as well as potentially catastrophic effects on roads, bridges, and homes. Associated water quality and health concerns could also be issues. Factors that influence the potential severity of a full or partial dam failure or dam incident are the amount of water impounded; the density, type, and value of development and infrastructure located downstream; and the speed of failure.

Controlled release or spillway flooding: inadequate spillway capacity often results in excess overtopping flows, though the potential for flooding as a result of discharge from dam outlet structures or spillways could be expected during excessive rain events. However, controlled release of water from dams is a measure that can prevent or minimize spillway flooding or structure failure, by regulating capacity in a managed way. Even controlled release can lead to unwanted or unpredicted flooding, depending on environmental and weather conditions, or even human error.

In general, there are three types of dams: concrete arch or hydraulic fill, earth-rockfill, and concrete gravity. Each type of dam has different failure characteristics. A concrete arch or hydraulic fill dam can fail almost instantaneously: the flood wave builds up rapidly to a peak then gradually declines. An earthrockfill dam fails gradually due to erosion of the breach: a flood wave will build gradually to a peak and then decline until the reservoir is empty. And, a concrete gravity dam can fail instantaneously or gradually with a corresponding build-up and decline of the flood wave.

Location
Limited – According to the U.S. Army Corps of Engineers’ National Inventory of Dams database, last updated in 2018, there are four potential dams of concern upstream of the City of South Lake Tahoe.

These dams have been constructed for flood control, snowmaking and irrigation storage, wastewater management, recreation, and stock watering purposes. Of these dams of concern, two are considered to pose high hazards, one is of significant hazard, and one is of low hazard. 530
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-34 The Echo Lake Dam is a roller-compacted concrete dam
built on the southeast corner of Lower Echo Lake. It is located 7.5 miles to the southwest of the City of South Lake Tahoe near Echo Summit. The dam storage capacity
is 1,860 acre-feet. This is a high-hazard dam owned by El Dorado Irrigation District, with an Emergency Action Plan (EAP) in place.

The Emergency Effluent Holding Dam is in the highhazard category and was built in 1961. It is owned by STPUD. It is located close to the City’s wastewater
treatment facility. This dam has a storage capacity of 184 acre-feet. An EAP for this dam is not in place.

The Fallen Leaf Lake Dam is located 4.3 miles west of the City of South Lake Tahoe. The dam storage capacity is
6,800 acre-feet. This significant-hazard dam is owned by the United States Department of Agriculture (USDA) Forest Service. An EAP is not in place for this dam. Given the distance of this water body and dam from the City and the surrounding topography, if there was a dam incident or failure, it is not expected to inundate the City.

Finally, the Tallac Dam is the closest to the heart of the City of South Lake Tahoe, located within Tahoe Keys – a waterfront community within the City of South Lake Tahoe. This dam has a storage capacity of 176 acre-feet. This is a low-hazard privately-owned dam. There is no EAP in place. Table 4-9 below details the dams that could potentially affect the City of South Lake Tahoe given their close proximity and potential to inundate if they were to fail. Figure 4-5 illustrates the locations of the four dams of concern near the City. The potential inundation areas are based on the best available data at the time of this plan update. It is important to note that the inundation areas shown do not represent all dams that pose a risk; some of this information is not available in GIS or allowed for release in a public document.

Table 4-9 Characteristics of the Dams of Concern Upstream of the City of South Lake Tahoe Hazard
Rating
Dam
Name
River
Drainage
Downstream
Community
Dam
Type
Dam
Height
(in Feet)
Storage
Capacity
(AcreFeet)
Emergency
Operations
Plan
Dam Owner
High Echo Lake Echo Creek
River
South Lake
Tahoe
RCC 14 1,860 Yes El Dorado
Irrigation
District
High Emergency
Effluent
Holding
Tributary to
Heavenly
Valley Creek
South Lake
Tahoe
Earth 27 184 No STPUD
Significant Fallen Leaf
Lake
Taylor Creek
River
Fallen Leaf
Lake
Unknown 12 6,800 No USDA FS
Low Tallac Off-Stream
River
South Lake
Tahoe
Gravity 11 176 No Wooldridge
and Jarvis
Source: U.S. Army Corps of Engineers’ National Inventory of Dams, 2018 Note: 1 acre-foot = 325,851 gallons
The City’s 2008 HMP noted one potential upstream dam of concern along Heavenly Valley Creek.

Heavenly Valley Creek is located in a small, high elevation forested watershed in the southeastern part of the Lake Tahoe Basin, in El Dorado County, California outside of the City limits. It is a tributary to Trout Creek in the southeastern portion of the Lake Tahoe watershed. Sky Meadow Reservoir is an approximate Echo Lake Dam is a high-alpine concrete dam located
along the southern end of Lower Echo Lake near Echo
Summit. It is owned by El Dorado Irrigation District
and has an Emergency Action Plan in place in the
event of a dam failure or incident.

Photo Credit: Travel Blog 2017
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-35 25-acre reservoir located on a tributary to Heavenly Valley Creek. It was constructed in 1978 in the Heavenly Valley Creek drainage to store water for snowmaking and irrigation at Heavenly Mountain Resort. The reservoir receives natural inflow from a 55-acre drainage area of Heavenly Valley Creek. This dam is not listed by the U.S. Army Corps of Engineers, the National Inventory of Dams, or Dams within Jurisdiction of the State of California.

Approximately 1,300 feet below the Sky Meadow Reservoir dam, the tributary joins the main stem of Heavenly Valley Creek. The creek flows southwest for approximately 1,200 feet before exiting the developed portion of the ski resort at 7,900 feet in elevation. Heavenly Valley Creek then drops another 1,300 feet over the next 1.5 miles to about 6,600 feet in elevation where the creek enters the southern end of the City limits. While this dam is located upstream of the City of South Lake Tahoe, given its small storage capacity, if it were to fail it is not anticipated to have substantial downstream impacts. 532
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-36 Figure 4-5 Dams Upstream of South Lake Tahoe and Best Available Inundation Mapping 533
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-37 Extent (Magnitude/Severity)
Negligible – Standard practice among federal and state dam safety offices is to classify a dam according to the potential impact a dam failure (breach) or mis-operation (unscheduled release) would have on downstream areas. The hazard potential classification system categorizes dams based on the probable loss of human life and the impacts on economic, environmental, and lifeline facilities. Dams are classified into the following three categories which identify their potential hazard to life and property (FEMA 333):
• High hazard indicates that a failure would most probably result in the loss of life; • Significant hazard indicates that a failure could result in appreciable property damage; • Low hazard indicates that failure would result in only minimal property damage and loss of life is unlikely; and
• There are also undetermined hazard dams that have not been rated or their hazard rating is not known.

Since there are two high-rated hazardous dams upstream of the City, there is some, though limited, potential for loss of life and/or property damage. Adjacent unincorporated portions of El Dorado County could also be affected by a dam failure upstream of the City, and the specific extent of impacts would depend on the nature of the failure, local emergency response capabilities, people and property found in the path of the dam inundation areas, and other such factors.

According to Figure 4-5, if Emergency Effluent Holding Dam were to fail/breach during a sunny day, the potential inundation would impact the communities and areas that bisect the City from east to west. The potential inundation area would also include Lake Tahoe Community College and extend to Truckee Marsh, which is to the north of the City. If Echo Lake Dam were to fail due to a storm, the inundation would follow along Upper Truckee River, impacting the eastern portion of the City. The potential inundation area would include certain communities within Tahoe Keys and extend to Truckee Marsh.

Previous Occurrences
There is no history of dam incidents or failures affecting the City.

Probability of Future Occurrences
Unlikely – The City remains at risk of upstream dam failures or incidents, particularly from the two dams that are classified as high-hazard structures. Nevertheless, the potential exists for future dam incidents in the City or portions of it, but the likelihood of this is low. Uncontrolled or controlled release flooding, as well as spillway flooding below dams due to excessive rain or runoff, are more likely to occur than failures.

Climate Change Considerations
The potential for climate change to affect the likelihood of dam failure and incidents is not fully understood at this point. With a potential for more extreme precipitation events as a result of climate change, this could result in large inflows to reservoirs. However, this could be offset by generally lowering reservoir levels if storage water resources become more limited or stretched in the future due to climate change, drought and/or population growth. For example, changes in lake or reservoir levels during extreme precipitation events could exceed the existing operation capabilities of dams in the region, as noted in the Lake Tahoe Climate Change Vulnerability Assessment regarding the concrete gravity Lake Tahoe Dam in Tahoe City at the outlet of Lake Tahoe. For these reasons, climate change would have a low influence on dam incidents.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-38 Vulnerability Assessment
A dam incident can range from a small, uncontrolled release to a catastrophic failure. Vulnerability to dam failures is confined to the areas and populations subject to inundation downstream of the facility.

Secondary losses would include loss of the multi-use functions of the dam itself and associated revenues that accompany those functions, including potential potable water uses or critical irrigation for crops.

Property
In general, communities located below a high or significant-hazard dam and along a waterway are potentially exposed to the impacts of a dam failure. For reference, high-hazard dams threaten lives and property, significant-hazard dams threaten property only. Inundation maps that identify anticipated flooded areas (which may not coincide with known floodplains) are often produced for all high-hazard dams and are contained in the EAP required for each dam. The potential magnitude of a dam incident depends on the time of year and the base flow of the river when the incident or failure occurs. During the winter months, when the river flows are higher, the impact to the area would be much greater and evacuation times even shorter.

A GIS layer that contained inundation maps for Echo Lake Dam and Emergency Effluent Holding Dam was analyzed to quantify risk across the City limits. Table 4-10 summarizes the results of the GIS analysis and includes a population estimate based on the number of residential parcels exposed, multiplied by an average household size estimate from the U.S. Census. Out of the 11,757 improved parcels covering various property types such as commercial, industrial and residential within South Lake Tahoe City limits, five improved parcels, which take up 0.04% of the City’s total improved parcels, would be impacted if both dams were to fail. The inundation area would put 13 people’s lives at risk and result in $1,860,326 in losses.

Table 4-10 Summary of Dam Inundation by Dam
Dam Source Property Type Improved
Parcels
Population Property/Parcel Loss
Estimate
Echo Lake Residential 2 5 $791,741
Emergency Effluent Holding Residential 3 8 $1,187,612
Total 5 13 $1,979,354
Source: California DSOD, National Inventory of Dams, El Dorado County Assessor’s Office Although both Fallen Leaf Lake Dam and Tallac Dam do not have dam inundation mapping available, it is expected that if either were to fail, neither would impose much risk on areas near the City based on their location and the surrounding topography. Also, although Echo Lake has a larger water storage capacity, given there was no previous dam inundation event that happened in the City and there is an EAP in place for Echo Lake Dam, together with HMPC input, dam failure incidents are unlikely in the areas upstream of the City. The potential exists for future dam incidents in the City or portions of it, but the likelihood of this is low.

People
Persons located downstream of a dam are at risk of a dam failure, though the level of risk can be tempered by topography (specifically where populations are located within the inundation path of a dam but at higher elevations), amount of water in the reservoir/damming structure, and time of day of the breach. Injuries and fatalities can occur from debris, bodily injury, and drowning. Once a dam has breached, standing water presents all the same hazards to people as floodwater from other sources.

People in the inundation area may need to be evacuated, cared for, and possibly permanently relocated.

Impacts could include hundreds or thousands of evacuations and likely casualties, depending on the dam involved.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-39 Population impacts are noted in Table 4-10, and total people at risk were calculated by multiplying the average number of persons per household in the City (2.53) times the number of residential parcels where dam inundation occurs. Based on the best available data accessible at this time of the analysis, an incident at the Echo Lake Dam would potentially put five people at risk. An incident at the Emergency Effluent Holding Dam would potentially put eight people at risk. If both dams were to have an incident, a total of 13 people’s lives would be at risk. Given that both Emergency Effluent Holding Dam and Echo Lake Dam are two high-rated hazardous dams, if a failure/breach were to happen, both dams could threaten lives downstream.

As mentioned above in Section 2.8 Social Vulnerability, the CDC ATSDR SVI Tool shows that there is one census tract in the central-to-north portion of the City with a relatively high vulnerability. California DWR DAC Mapping Tool also shows that there is also one severely disadvantaged community census tract to the west of the center of the City. The location of these disadvantaged census tracts somewhat overlaps the potential inundation areas of Emergency Effluent Holding Dam and Echo Lake Dam, meaning that socially vulnerable or sensitive populations in the City are more likely to be exposed to the potential impact.

Economy
Extensive and long-lasting economic impacts could result from a major dam failure including the longterm loss of water in a reservoir after a failure event. A major dam failure or incident and loss of water from the associated reservoir could include direct damages and indirect disruption of business and industry.

Critical Facilities and Infrastructure
A total dam failure can cause catastrophic impacts to areas downstream of the water body, including critical infrastructure and essential facilities. Dam incidents may result in less severe downstream impacts, depending on the severity of the incident. Any critical asset located under the dam in an inundation area would be susceptible to the impacts of a dam incident. Of particular risk would be roads and bridges that could be vulnerable to washouts, further complicating response and recovery by cutting off impacted areas. Risk to specific facilities could be considered sensitive information, especially those such as water treatment facilities or water delivery systems that may provide potable water for the local population.

A GIS layer that contained inundation maps for Echo Lake Dam and Emergency Effluent Holding Dam was analyzed to quantify risk on the critical facilities and infrastructure identified in Section 4.2. Table 4-11 summarizes the results of the GIS analysis by FEMA lifeline and the dam sources. Out of the total 195 critical facilities and infrastructure of concern, seven would be impacted if both dams were to fail. Among these seven critical facilities and infrastructure, three belong to the Food, Water, Shelter lifeline, one belongs to the hazardous material lifeline and another three belong to the Transportation lifeline.

Table 4-11 Facilities within the Dam Inundation Hazard by FEMA Lifeline Dam Source FEMA Lifeline Echo Lake Emergency Effluent Holding Total Communications 0 0 0
Energy 0 0 0
Food, Water, Shelter 1 2 3
Hazardous Material 0 1 1
Health and Medical 0 0 0
Safety and Security 0 0 0
Transportation 3 0 3
Total 4 3 7
Source: California DSOS, National Inventory of Dams, HMPC Input, HIFLD 2021; Wood Analysis of City and HIFLD datasets 536
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-40 Historic, Cultural, and Natural Resources
Dam failure effects on the environment would be similar to those caused by flooding from other causes.

Water could erode stream channels and topsoil and cover the environment with debris. For the most part, the environment is resilient and would be able to rebound from whatever damages occur, though this process could take years. Historic and cultural resources could be affected just as housing or critical infrastructures would, were a dam to fail and cause downstream inundation that could further erode surfaces or cause scouring of structural foundations. Given there was no previous dam inundation event that happened in the City, together with HMPC input, dam failure incidents are unlikely in the area.

Nevertheless, the potential exists for future dam incidents, though the likelihood of this is low. Combined with the GIS analysis result showing the damage of a potential dam inundation event, the actual risk to historic, cultural, and natural resources is Medium.

Future Development
Areas slated for future development should take into consideration potential impacts from dam failure risk upstream and should attempt to overlay the existing dam inundation maps with proposed future development. In the case of a dam failure, inundation would likely follow existing FEMA-mapped floodplains, which contain development restrictions for areas in the one percent annual chance floodplain, but it could exceed those floodplains and affect areas that are not regulated for flood hazards. Also, development below a low or undetermined hazard dam such as the Tallac Dam could increase its hazard rating. Finally, added development could compromise dams and reservoir resources if populations depend on them for critical needs such as potable water during or after a dam failure event.

Risk Summary
• The overall significance of dam inundation in the City is Low. • There are four dams of concern that fall upstream of the City: Echo Lake Dam, Fallen Leaf Lake Dam, Emergent Effluent Holding Dam, and Tallac Dam.
• Echo Lake Dam is considered a high-hazard dam and is owned by El Dorado Irrigation District. It is located about 7.5 miles southwest of the City and its storage capacity is 1,860 acre-feet. This is the only dam with an EAP in place.
• The second dam of concern is the Emergent Effluent Holding Dam. It is considered a high-hazard dam and located around 1.7 miles southeast of the City. It is owned by STPUD and has a storage capacity of 184 acre-feet.
• The third dam of concern is Fallen Leaf Lake Dam. It is located to the west of the City of South Lake Tahoe, about 4.3 miles away from the City. The dam storage capacity is 6,800 acre-feet. • The last potential dam of interest is the Tallac Dam, a low-hazard dam with a capacity of 176 acrefeet. • GIS spatial analysis shows that five improved parcels, which take up 0.04% of the City’s total improved parcels, would be impacted if both Echo Lake Dam and Emergency Effluent Holding Dam were to fail.

The potential inundation would put 13 people’s lives and around $1,860,326 parcel value at risk.

4.3.3 Drought
Hazard Description
Drought is a gradual phenomenon. Although droughts are sometimes characterized as emergencies, they differ from typical emergency events. Most natural disasters, such as floods or forest fires, occur relatively rapidly and afford little time for preparing for disaster response. Droughts occur slowly, many times over a multi-year period, and it is often not obvious or easy to quantify when a drought begins and ends. 537
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-41 Drought is a complex issue involving many factors; it occurs when a normal amount of moisture is not available to satisfy an area’s usual water-consuming activities. Drought can often be defined regionally based on its causes or effects:
• Meteorological drought is usually defined by a period of below-average water supply. • Agricultural drought occurs when there is an inadequate water supply to meet the needs of the State’s crops and other agricultural operations such as livestock. • Hydrological drought is defined as deficiencies in surface and subsurface water supplies. It is generally measured as streamflow, snowpack, and as lake, reservoir, and groundwater levels. • Socioeconomic drought occurs when a drought impacts health, well-being, and quality of life, or when a drought starts to have an adverse economic impact on a region.

The California DWR says the following about drought:
“One dry year does not normally constitute a drought in California. California’s extensive system of water supply infrastructure—its reservoirs, groundwater basins, and inter-regional conveyance facilities—mitigates the effect of short-term dry periods for most water users. Defining when a drought begins is a function of drought impacts to water users. Hydrologic conditions constituting a drought for water users in one location may not constitute a drought for water users elsewhere, or for water users having a different water supply. Individual water suppliers may use criteria such as rainfall/runoff, amount of water in storage, or expected supply from a water wholesaler to define their water supply conditions.”
The drought issue in California is further compounded by water rights. Water is a commodity possessed under a variety of legal doctrines. The prioritization of water rights between farming and federally protected fish habitats in California is part of this issue.

Drought impacts are wide-reaching and may be economic, environmental, or societal. Also, during a drought, water allocations go down, which results in reduced water availability. Voluntary water conservation measures are typically implemented during extended droughts. A reduction of electric power generation and water quality deterioration are also potential problems. Drought conditions can also cause soil to compact and not absorb water well, potentially making an area more susceptible to flooding.

Location
Significant – Drought is a regional hazard, and during severe drought conditions, it can affect the entire State of California with varying levels of dryness. In other words, drought affects all aspects of the economy and environment, and community simultaneously. The most significant impacts associated with drought in the City’s Planning Area are those related to water-intensive activities such as municipal usage and general water supply (e.g. irrigation for parks and open spaces), wildfire protection (including relief and response activities), commerce, and tourism.

According to the City of South Lake Tahoe’s 2011 General Plan (2011) and the STPUD 2020 Draft UWMP, the City relies on groundwater for the majority of its water supply. The STPUD supplies drinking water to the majority of the City, in addition to three small private water companies. These additional small private water companies include the Tahoe Keys Water Company (separate administration department of the Tahoe Keys Property Owners Association [TKPOA]), Lukins Brothers Water Company, Inc., and Lakeside Park Mutual Water Company. These water companies provide approximately 2,600 total additional connections, located within or adjacent to STPUD’s service area. 538
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-42 STPUD’s service area encompasses 27,000 acres in eastern El Dorado County on the southern shore of Lake Tahoe, including the City of South Lake Tahoe and serves over 3,000 connections per year. The 2020 water supply and projected future supply provided by STPUD in acre-feet are displayed in Table 4-12.

Table 4-12 STPUD’s Current Water Supply and Projected Future Supply Water Supply 2020
Supply
2025
Projected
Supply
2030
Projected
Supply
2035
Projected
Supply
2040
Projected
Supply
Groundwater 5,778 AF1 6,5.886 AF 5,884 AF 6,014 AF 6,147 AF Recycled Water 0 0 0 0 0
Water Conservation 0 0 0 0 0
TOTAL 5,778 AF 6,,886 AF 5,884 AF 6,014 AF 6,147 AF
Sources: South Tahoe Public Utilities District, 2020 Draft UWMP.

Notes:

1. One Acre-Foot = 43,560 cubic feet.

STPUD also owns and operates an award-winning wastewater collection and treatment system, which produces effluent at recycled water standards. The system collected 3,498 AF of wastewater in 2020 and can treat 23.6 AF per day. Because the Lahontan Regional Water Quality Control Board prohibits the use of recycled water within the Tahoe Basin STPUD cannot reuse recycled water within the area. City. Instead, all the effluent is pumped over Luther Pass south of the City to Alpine County and used for agricultural purposes.

STPUD has six fire hydrants installed along a short section of its export pipeline. These hydrants provide emergency fire suppression to the residential community and STPUD’s critical wastewater pumping station at the base of Luther Pass. According to STPUD’S 2020 UWMP and 2020 Water shortage Contingency Plan, STPUD applies a three-stage plan during declared water shortages, which also applies to catastrophic loss of water. Stage 1 involves up to 20 percent supply reduction water shortage and is for normal or wet year supply or minor supply reduction conditions. Stage 2 involves 25 to 30 percent to 50 percent supply reductions in water shortage and is for significant water shortages, such as a regional power outage. Stage 3 involves a 50 percent or more shortage and is for significant supply reduction under water emergencies. Emergency conditions consist of wildfire events or events where there is an extended regional power outage.

STPUD also has developed an EOP, which guides response to unpredicted catastrophic events that might impact water delivery for all levels of emergency, from minor accidents to major disasters. In addition, the district has prepared a LHMP, which was adopted in 2017.

In terms of water conservation, STPUD is a member of the California Urban Water Conservation Council.

STPUD has been following best management practices (BMPs) and maintains an annual budget of $173,000 to fund its conservation program. STPUD has an established conservation coordinator position that manages and supervises STPUD’s conservation program and BMP implementation. In addition, STPUD maintains a school education program and is a member of the South Tahoe Environmental Education Coalition, where STPUD educates students through the Coalition’s various activities and weeklong camps.

The Tahoe Keys Water Company serves the next largest segment of the South Lake Tahoe community comprised of residential customers, including approximately 1,194 single-family homes and 335 townhouses within the TKPOA. The Tahoe Keys Water Company also serves four commercial customers, including the Tahoe Keys Marina & Yacht Club and Tahoe Keys Office Center. Water is conveyed within the TKPOA from three groundwater wells and via water conveyance pipelines managed by the Tahoe Keys 539
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-43 Water Company. The Tahoe Keys Water Company also manages water supply and water quality monitoring. As of 2021, one of the wells needed to be shut down due to elevated levels of naturally occurring uranium and due to uranium levels exceeding the maximum contaminate level (MCL). The remaining well was not able to meet the peak demands through the summer months given the high demands required for landscape irrigation within the community. While non-turf irrigation was recently permitted, the Tahoe Keys Water Company still has limited groundwater capacity for homeowners to resume irrigating their lawns (TKPOA 2021).

Lukins Brothers Water Company, Inc. is one of the smaller water companies that provide domestic water service to over 975 customers through 58,000 feet of water mains. They also provide fire protection through fire hydrants in their service area, which is entirely within the City’s Planning Area (City limits).

Additionally, Lakeside Water is a small private water company that is part of Lakeside Park Association (LPA), which is comprised of residential homes, vacation rentals, long-term rentals, hotels, motels, condos, timeshares, restaurants, and retail businesses. These residences and facilities are located at Lakeside Beach and the historic Lakeside Marina. Lakeside Water provides water to its customers within LPA via one groundwater well, a small water treatment plant, and a storage tank.

Sustainable Groundwater Management Act of 2014 (SGMA)
Groundwater resources play a significant role in the development, growth, and sustainability of the City and the overall region. As the major water supplier to the City, STPUD developed and adopted a Groundwater Management Plan (GMP) in 2005. STPUD has been serving as the leading Groundwater Sustainability Agency (GSA) for the region by addressing safe yield, and all requirements of the SGMA and other rules and criteria developed and approved by the State. STPUD’s GMP and ongoing SGMA efforts will provide the framework to manage the basin sustainably to prevent overdrafts or other detrimental results related to groundwater quality.

Back in the 1990s, the fuel additive – methyl tert-butyl ether (MTBE) was the primary limiting factor to the district’s supply and operations. However, with new well installations and recent distribution system improvements, the district has returned to pre-MTBE production capability. Historically, drought conditions have not impacted the Tahoe Valley South Subbasin, even during the drought of 1985-1991 (STPUD 2020). Also, according to the UWMP, the district does not anticipate any detrimental effects to the groundwater basin due to climatic changes (STPUD 2020).. Meanwhile, STPUD’s groundwater studies confirm that the wells that serve as their water supply are supported by Lake Tahoe. During the drought of 1985-1991, lake levels dropped 10 feet but the static water level decline observed in STPUD’s wells was less than four feet and this drop was observed in only a few wells (STPUD 2010). According to the UWMP, within the STPUD service area, there is sufficient groundwater supply for the projected water demands.

There is also no need to identify additional supplies from other regions. STPUD will pump sufficient supply to meet the demands during the single and multiple dry year scenarios outlined in the 2015 UWMP, without requiring a reduction in demand or supplemental supplies. Furthermore, as addressed in the 2020 UWMP, STPUD plans to be proactive in addressing groundwater contamination.

All of California have been experiencing significant drought and water shortages since 2011 and only recently did the majority of the State come out of drought and then return to drought conditions again in 2021. In January 2014, the Governor declared an emergency proclamation due to multiple years of drought (2012-2016 drought). The proclamation called on citizens to reduce water use by 20 percent; with a subsequent executive order that directed urban water agencies to reduce water use by 25 percent. In September 2014, the Governor signed a three-bill package (California Senate Bills 1168 and 1319, and Assembly Bill 1739), known as SGMA of 2014. The SGMA established local GSAs to manage groundwater sustainability within the groundwater sub-basins defined by the California DWR, while as). The Governor 540
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Extent (Magnitude/Severity)
Limited – Extent can be measured according to a scale developed by the United States Drought Monitor, which measures drought in five categories: Abnormally Dry (D0), Moderate Drought (D1), Severe Drought (D2), Extreme Drought (D3) and Exceptional Drought (D4). El Dorado County is vulnerable to all levels of drought, which are further subject to the effects of climate change, precipitation trends, and wet and dry periods. Drought can have a widespread impact on the environment and economy in the Planning Area, but it typically does not result in loss of life or damage to property. Instead, drought may have an impact on business, and the movement of goods and services related to commodities, tourism and recreation, and water supply sectors in the South Lake Tahoe Region.

According to the City of South Lake Tahoe’s 2008 Natural Hazard Mitigation Plan, the greatest effects from drought are economic. Impacts on recreation operations and the forest products industry can be devastating. During the winter, lack of snowfall can keep recreation facilities such as resort operators closed, causing a tremendous financial hardship. In the summer, camping, as well as water-related activities, may be limited. In general, the lack of water caused by drought often means fewer visitors to the City, which also equates to lowered City sales tax revenues. Besides the potential impact on the City’s economy, drought also raises concern for other natural hazards, among which wildfire would be the most dangerous and damaging hazard as a result of long-term drought conditions in the Tahoe Basin.

According to the 2020 UWMP, 71 of potable and raw water demands are residential, 13% are commercial (including institutional)office, retail and for landscape, resort accounts), with another 16% as non-metered water use such as firefighting, flushing, leaks, water theft, or meter inaccuracies.

It can be assumed that three main factors affect water demands: climatic, demographic, and economic.

These are described below and are expected to influence water demands in the future, as they have in the past.
• Climatic. The annual average maximum temperature and minimum temperature for South Lake Tahoe are 58.2 and 28 degrees Fahrenheit respectively. The weather in South Lake Tahoe is warm and temperature with a mean annual temperature of 61 degrees Fahrenheit. The average annual precipitation is about 16.27 inches based on a 48-year period from May 1, 1968 to June 9, 2016 (Western Regional Climate Center (WRCC) 2021). For the City, drought occurs when winter precipitation fails to materialize. When the winter storms fail to arrive or fail to provide substantial amounts of moisture, the potential for the development of drought arises. Although the City’s water supply fully relies on groundwater and drought generally introduces a threat to water supplies, STPUD is confident that there is sufficient supply to meet the demands during each of the single and multiple dry year scenarios, as mentioned above.
• Demographic. Since water use is related to demographics and population change, an accurate description of population and housing stock in the service area serves as a basis for water planning activities. According to California DOF data, the City’s population was 22,847 in 2020. The City’s annual population growth rate is currently at around 0.8%. The 2020 UWMP projects there will be approximately 30,381 people by 2025 and 31,526 people by 2035. • Economic. Commercial water users have the second-highest water demand after residential users (both single-family and multi-family). According to the STPUD’s 2020 UWMP, commercial water users' demand for potable and raw water is projected to increase from a volume of 716 AF in 2025 to 743 AF in 2035 and 771 AF in 2045, or by 7 percent over the next 20 years. The City’s commercial water 541
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-45 supply and demand are already relatively high. As mentioned above, the City’s economy depends heavily on water-related recreational operators and facilities (e.g., ski resort snowmaking).

The magnitude or severity of drought across the City could vary and is difficult to predict. However, understanding the total population affected as well as economy and resources vulnerable provides insight on how to estimate potential losses and damages to the City’s assets; drought-related information can be obtained and measured from the National Drought Mitigation Center’s Impact Reporter and Drought Monitor tools (United States Drought Monitor 2018; United States Drought Impact Reporter 2018).

Figure 4-6, Figure 4-7, and Figure 4-8 provide “snapshots in time” of the drought conditions in California as of July 2021, November 2018, and August 2015 (during the period of 2021’s worsening drought and the state-wise multi-year drought from 2012- 2017). The snapshots selected are instrumental in depicting both the historic and potential change in drought’s geographic range and severity in El Dorado County (circled in blue). These maps were extracted from the National Drought Mitigation Center and consider several factors including the Palmer Drought Index, Soil Moisture Models, United States Geological Survey (USGS) Weekly Streamflows, Standardized Precipitation Index, and Satellite Vegetation Health Index (United States Drought Monitor 2018).

Figure 4-6 U.S. Drought Monitor Conditions for California, July 2021 Source: National Drought Mitigation Center, 2021
City of
South Lake Tahoe
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-47 Figure 4-8 U.S. Drought Monitor for California: August 4, 2015 Source: National Drought Mitigation Center, 2018
Previous Occurrences
Historically, California has experienced multiple severe droughts. Figure 4-9 depicts California’s multi-year historical dry periods from 2000-2021.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-48 Figure 4-9 Drought Conditions in California – 2000 – 2021 Source: U.S. Drought Monitor https://droughtmonitor.unl.edu/Data/Timeseries.aspx Since the year 2000, there have been several cases of multi-year droughts across California; these are described below:
2007-2009 – Water years 2007-2009 were the seventh driest three-year period in the measured record for statewide precipitation and the fifteenth driest three-year period for DWR 8-station precipitation index (a rough indicator of potential water supply available to the State Water Project and Central Valley Project).
2012-2017 – The water years of 2012-14 stand out as California’s driest three consecutive years in terms of statewide precipitation. The drought occurred at a time of record warmth in California, with new climate records set in 2014 for statewide average temperatures. On January 17, 2014, California declared a drought state of emergency, and during this time the state- assisted farmers and communities that were most impacted by the drought conditions and helped with drinking water shortages. The State also directed all State agencies to use less water and expand their water conservation campaigns. On April 17, 2017, Executive Order B-40-17 was issued, which officially ended the drought state of emergency in California, except for Fresno, Kings, Tulare, and Tuolumne counties. 2021-Present – On June 28, 2021, El Dorado Irrigation District (EID) declared a drought emergency and authorized a Stage 1 Water Alert for all district service areas. Stage 1 actions target up to a 15 percent demand reduction compared to 2020 levels through the implementation of voluntary customer actions. (EID 2021).

Table 4-13 summarizes the drought-related disaster declarations proclaimed for El Dorado County from 1976 through 2021. These declarations include those from FEMA and the USDA’s Secretary of Agriculture.

Table 4-13 Disaster Declarations and Proclamations Related to Drought in El Dorado County Declaration or Order Date
EM-3023 (FEMA) 1/20/1977
S3452 (Secretary of Agriculture) 2012
S3379 (Secretary of Agriculture) 2012
S3351 (Secretary of Agriculture) 2012
S3283 (Secretary of Agriculture) 2012
S3495 (Secretary of Agriculture) 2013
S3569 (Secretary of Agriculture) 2013
S3797(Secretary of Agriculture) 2014
S3743 (Secretary of Agriculture) 2014
S3638 (Secretary of Agriculture) 2014
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S3637 (Secretary of Agriculture) 2014
S3626 (Secretary of Agriculture) 2014
S3638 (Secretary of Agriculture) 2014
S3626 (Secretary of Agriculture) 2014
S3963 (Secretary of Agriculture) 2015
S3789 (Secretary of Agriculture) 2015
S3784 (Secretary of Agriculture) 2015
S3952 (Secretary of Agriculture) 2016
S3953 (Secretary of Agriculture) 2016
S4163 (Secretary of Agriculture) 2016-2017
S4697 (Secretary of Agriculture) 2020
S4916 (Secretary of Agriculture) 2020-2021
S4636 (Secretary of Agriculture) 2021
Source: USDA Disaster Designations 2019; California SHMP 2018; FEMA Figure 4-10 graphically displays the amount of drought-related reported impacts to El Dorado County (United States Drought Impact Reporter 2019). While it is difficult to extract the impacts specifically affecting the City of South Lake Tahoe, a total of 164 reports were made within El Dorado County between January 1, 1950, and July 24, 2021. It is assumed that these drought-related impacts for areas across El Dorado County are likely to have also affected the City of South Lake Tahoe at some point or to some extent. Based on the summary of negative effects to the County since 1950, the categories of water supply/quality have had the most reports, followed by relief, response, and restrictions operations and society and public health. Plants & wildlife, Agriculture and Tourism & Recreation have also suffered the effects of drought, but to a lesser extent.
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Source: National Drought Mitigation Center Drought Impact Reporter, 2021 Probability of Future Occurrences
Likely – Historical drought data for California and more particularly the El Dorado County municipalities indicate there have been significant droughts and negative effects from water shortages in the past and the present. Based on this data, droughts are likely to affect the City and surrounding parts approximately every five years; some of these droughts may persist for multiple years.

Climate Change Considerations
Scientific studies prepared for various California climate assessments and adaptations strategies show that drought conditions in California are likely to become more frequent and persistent over the next century due to climate change. Temperatures are warming, heat waves are more frequent, and precipitation has become increasingly variable (Natural Resources Agency 2018a). Water resources are also already 547
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The recent drought conditions over the past decade underscore the need to examine water supply and distribution management, conservation, and use policies. As stated in the City of South Lake Tahoe’s 2008 Natural HMP, conservation of water resources should not be a response to drought conditions, but instead, it should be a conscious practice at all times. Citizens should always be prepared for the onset of drought conditions. The more residents of the County that work to protect the quantity and quality of ground and surface water resources, the more effectively and efficiently the City will be able to address drought situations. Nevertheless, although the City’s water supply fully relies on groundwater and drought often causes a threat to water supplies, as previously noted, the STPUD’s forecasts there is sufficient supply to meet the demands during each of the single and multiple dry year scenarios. (STPUD 2020).

According to California’s CAS, also referred to as Safeguarding California Plan: 2018 Update, climate change is likely to significantly diminish California’s future water supply. As a result, the state must change its water management, as climate change will create greater competition for limited water supplies (California Natural Resources Agency 2018b). According to El Dorado County’s 2017 Climate Change and Health Profile Report, during the next few decades, scenarios project average temperatures to rise between 3.7 °F and 6.5 °F in El Dorado County. Exacerbated by climate change, increasing temperatures and changes in precipitation may lead to intensified drought conditions. Drought decreases the availability and quality of water for humans, which includes reduced water levels to fight wildfires.

Drought may also increase exposure to health hazards including wildfires, dust storms, extreme heat events, flash flooding, degraded water quality, and reduced water quantity (El Dorado County’s 2017 Climate Change and Health Profile Report).

According to the 2021 UC Davis Tahoe: State of the Lake Report, based on Climatic Water Deficit calculation, drought conditions will intensify in the coming decades. Meanwhile, for Tahoe City, the average annual precipitation for 2020 was well below its long-term average. Combined with the low precipitation of winter 2021, drought conditions are returning to the Lake Tahoe Region. Moreover, drought conditions are predicted to result in low lake levels for Lake Tahoe – lower than Lake Tahoe’s natural rim. In addition, the 2020 UC Davis Tahoe: State of the Lake Report notes that wildfire and drought will continue to impact the health of Tahoe’s forests – sugar pine distribution, for example, may decline, which experienced tremendous reduction during the 2012 – 2016 drought.

The 2020 Integrated Vulnerability Assessment of Climate Change in the Lake Tahoe Basin also discussed climate change and drought, as well as their combined impacts on the region. Climate change will cause interannual variability in precipitation to increase, leading to more extreme droughts. Drought stress will increase significantly by the end of the century. Aggravated by climate change, extreme hydrological events such as floods and rain-on-snow events will happen more frequently and intensively. These extreme events together with extended drought will lead to higher flow runoff events and corresponding impacts on erosion, pollutant transport, and damage to infrastructure. Meanwhile, warmer temperatures, along with longer droughts and increased evaporation, may cause the surface of Lake Tahoe to go below its natural rim more frequently, which would affect how the Bureau of Reclamation manages the dam at Tahoe City for water supply to downstream communities. Furthermore, as noted in California’s Fourth Climate Change Assessment Sierra Nevada report drought and diminished snowpack will result in a loss of skiing days at ski resorts and likely will affect the availability of service jobs in the region. A loss of snowpack will also likely have an impact on other types of recreation in the region, including boating and fishing,
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Property
Standing dead trees could fall and pose a risk to people, buildings, power lines, roads and other infrastructure. In addition, drought-impacted trees become susceptible to diseases and insect infestations (i.e. bark beetle) further adding to the risk of tree mortality and related potential impacts.

In summary, drought impacts are wide-reaching and may be economic, environmental, and societal. The most significant impacts associated with drought for the City are those related to water-intensive activities, such as municipal water use, commerce, tourism, and recreation. The vulnerability of a waterintensive activity to the effects of drought usually depends on its water demand, whether the demand is met, and what water supplies are available to meet the demand. As previously mentioned, the groundwater basin supply is highly reliable with no anticipated water supply shortage and there is sufficient supply to meet the demands during each of the single and multiple dry year scenarios.

According to the Drought Impact Reporter the El Dorado County recorded a total of 164 impacts to drought in the survey period between 1/1/1950 and 7/24/2021 (72-year period). Of these, the majority of the impacts were associated with Water Supply and Quality and Relief, Response, and Restrictions. These statistics are shown in Figure 4-10 (above). While the Drought Impact Reporter data reflects impacts at the county level, the data should be used to develop an ongoing record of drought impacts that can be more specifically tied to events that occur within the City to better understand city-specific vulnerable sectors and impacts.

People
According to 2020 UWMP, the City of South Lake Tahoe’s population was 29,824 in 2020. The City’s annual population growth rate is currently at around 0.8%, outpacing the state and nation’s current population growth rate (around 0.38% and 0.5% respectively), and is projected to reach 31,526 by 2035.

This population growth would add additional strain to the groundwater supplies, although STPUD is confident in meeting current and future water demand, given that the groundwater basin supply is highly dependable. There are also several initiatives in the UWMP and the City’s 2011 General Plan that emphasize water conservation. Water conservation will also ensure that the existing groundwater remains operational during severe drought conditions and readily available during emergencies.

Drought can also cause or worsen public health problems related to poor water quality, and health problems can become exacerbated due to dust. The nearshore regions of Lake Tahoe are at a growing risk with the presence of filamentous algae that wash up on the beaches and decompose. Worsened by climate change, warmer water temperature, lower and unpredictable precipitation, extended drought and higher nutrient will aggravate the algae’s growth, which further degrades nearshore water quality. (2021 UC Davis Tahoe: State of the Lake Report)
Generally, drought may require the conservation of water resources, which means that water use is restricted to essential uses, which may reduce watering for landscaping. The community may also exhibit a range of abilities to prepare for, respond to, and recover from drought hazards, as these conditions impact populations with health-related issues related to heat-related illness, respiratory problems, and people who work outdoors. These conditions can also impact lower-income populations, as food and water prices increase. There are sensitive and socially vulnerable populations that may be the most susceptible to water restrictions and health-related illnesses. Socially vulnerable populations may also be sensitive to increases in water rates and food prices.
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Drought impacts on the local and regional economy can be difficult to quantify but can be extensive and long-lasting depending on the circumstances during and after a severe drought event. If water resources are limited, effects would be more severe for industries that rely on large amounts of water, and any prolonged drought would intensify these impacts. Sectors critical to the economy such as commerce, distribution, related environmental resources, municipal and industrial water supply, key city assets, energy generation, and even socioeconomic aspects can be affected due to lack of or reduced quality of water resources.

As mentioned above, according to the City of South Lake Tahoe’s 2008 Natural Hazard Mitigation Plan, the greatest effect from drought for the City is economic. Impacts on recreation operations and the forest products industry can also be devastating.

Critical Facilities and Infrastructure
The most direct impact of drought will be on the City’s water supply. Drought can also directly affect the water storage, treatment, distribution, and conveyance systems. Landscaping around City facilities may no longer be maintained during water restrictions, but the risk within the City will be largely aesthetic.

Historic, Cultural, and Natural Resources
Severe, prolonged drought can impact the natural
environment. Wildlife and natural habitats including the aquatic resources within the Upper Truckee River and
Trout Creeks and Lake Tahoe can be affected due to
fluctuating lake levels during extended droughts
compared to periods of rapid increases in the lake level due to heavy precipitation events. Such fluctuations can impact available habitat for native forage fish to spawn and rear their young, and the habitat within the Lake
Tahoe nearshore environment is already limited (California Tahoe Conservancy 2020).

The timing of seasonal snowmelt shifts toward earlier in the spring, while there will be less soil moisture later in the year, with consequential impacts on drought-sensitive
vegetation and dependent species. There are likely to be longer-term changes in forest composition and
distribution. Drought stress and widespread outbreaks by bark beetles will kill more trees. Vegetation will also change due to a combination of drought, increased insect populations and pathogens, tree mortality, windthrow during extreme storms, and a greater risk of wildfire.

Moreover, riparian habitat is significantly threatened by increases in temperature and subsequent drought stress. Also, increased temperatures, longer growing seasons, reduced snowpack, and drought may reduce water levels in springs, streams, and wetlands, and increase moisture stress for many plants, especially in the summer. In addition, prolonged drought can also cause poor soil quality, loss of wetlands, and increased soil erosion that could increase pollutants in runoff and damage infrastructure (e.g., stormwater systems).

Finally, drought can aggregate other natural hazards. One of the most prevailing impacts of drought on the natural environment is the increased risk of wildfires, as seen during the 2017-2018 and 2021 wildfire Prolonged drought coupled with climate change
dropped Lake Tahoe below its natural rim of 6,223 feet
in 2021, which limited flows into the Truckee River.

Lake levels have occasionally gone below the rim, but
the frequency of this event is increasing. Water levels returned to above the natural rim in late October 2021
following a massive storm system that pushed through
northern California.

Photo Credit: Juliana Prosperi 2021
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-55 Figure 4-11 Drought-Related Tree Mortality in the South Lake Tahoe Region Note: Tier 1 High-Hazard Zones are areas where tree mortality directly coincides with critical infrastructure. They represent direct threats. 552
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As a result of both drought conditions and wildfires, standing dead trees could fall and pose a risk to people, buildings, power lines, roads, and other infrastructure. Tree mortality is also identified as a cascading impact that can affect (or worsen) other hazards, such as wildfire and wind conditions. For example, drought-impacted trees become susceptible to diseases and insect infestations (i.e. bark beetle), which further adds to the risk of tree mortality and related potential impacts.

The extent of tree mortality can be viewed as sub-set to the drought hazard. Those areas of the surrounding forest susceptible to drought comprise a large area in El Dorado County since tree mortality is related to other sub-factors specific to the species impacted such as tree age and soil composition.

Figure 4-11 above illustrates the extent of tree mortality in South Lake Tahoe and the surrounding region.

There are several Tier 1 High-Hazard Zones near the City of South Lake Tahoe, potentially imposing direct threats to critical infrastructure and facilities.

Furthermore, as mentioned in the People section, drought can degrade water quality. Also, together with climate change, longer droughts may cause the surface of Lake Tahoe to go below its natural rim more frequently. These consequences may result in reduced welfare benefits associated with recreational trips to the City. Impacts on the City’s historic and cultural building inventory may be negligible in comparison to the impacts on the natural resources. Similarly, the City’s open spaces and public lands can suffer during droughts; however, aesthetically these impacts may be minor.

Future Development
As described in STPUD’s 2020 UWMP, the district will have an adequate and reliable water supply for the City. As new development occurs in the City, it will be important to assess the availability and reliability of groundwater, ensuring that adequate water supplies exist to support new growth.

Risk Summary
• There have been two multi-year droughts since 1950. The most recent drought lasted from 2012 to 2017 and resulted in a declared state of emergency.
• 164 drought impact reports were made within El Dorado County between 1950 and 2021. • As of 2020, STPUD was supplying 5,778 acre-feet of water, the majority of which is supplied to residential users. The 2020 Draft UWMP projects that the demand for potable and raw water will increase to 6,147 acre-feet, or by around 26 percent by the year 2040. • The City of South Lake Tahoe’s population was 22,847 in 2020. The City’s annual population growth rate is currently at around 0.8%; future population growth might add additional strain to the water supply, particularly during future severe drought events. • Climate change is anticipated to have a high influence on drought and water supply, as climate change projections indicate the region will experience more frequent and intense droughts due to drier soil conditions in the summer months, leaving less water available for groundwater recharge.

Increased temperatures and drying conditions could also result in pest infestations, tree mortality, the increased potential for wildfires, and Lake Tahoe surface levels that fall below the natural rim. • The enforcement of water conservation policies will help ensure the City of South Lake Tahoe is more resilient to drought events in the future.
• Overall, the significance of extreme drought is Medium. 553
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4.3.4 Earthquakes
Hazard Description
An earthquake is the vibration of the earth’s surface caused by a sudden slip on a fault. Stresses in the earth’s outer layer push the sides of the fault together. Stress builds up, and the rocks slip suddenly, releasing energy in “seismic waves” that travel through the earth’s crust and cause the shaking that is felt during an earthquake. These seismic waves travel outward from the source of the earthquake and different speeds. The amount of energy released during an earthquake is usually expressed as a magnitude and is measured directly from the earthquake as recorded on seismographs. Another measure of earthquake severity is intensity. Intensity is an expression of the amount of shaking at any given location on the ground surface (see discussion in the Extent section). Seismic shaking is typically the greatest cause of losses to structures during earthquakes.

Seismic Hazards
Earthquakes can cause structural losses, injury, and possibly death, as well as damage to infrastructure such as water, power, gas, communication, and transportation networks and systems. The degree of damage depends on many interrelated factors. Among these are the magnitude, focal depth, distance from the causative fault, source mechanism, duration of shaking, high rock accelerations, type of surface deposits or bedrock, degree of consolidation of surface deposits, presence of high groundwater, topography, and the design, type, and quality of building construction.

Primary hazards associated with seismic activity include surface rupture along faults, ground shaking, and associated building failure. Secondary hazards result from the interaction of ground shaking with existing ground instabilities or facilities and include liquefaction, settlement, debris flows, landslides, tsunamis and seiches, and flooding or wildfires from broken pipelines, gas, or electrical infrastructure.

According to the U.S. Geological Survey (USGS) Earthquake Hazards Program, the following earthquake hazards can affect a community:

Ground Shaking
When movement occurs along a fault, the energy generated is released as seismic waves, which cause ground shaking. Ground shaking intensity varies with the magnitude of the earthquake, the distance from the epicenter, and the type of rock or sediment through which the seismic waves move. The geological characteristics of an area can be a greater hazard than the area’s distance to the earthquake epicenter.

Several Quaternary faults go through the City and/or in the vicinity of the City’s Planning Area. Both Tahoe Valley fault and East Tahoe fault go through the City. West Tahoe-Dollar Point fault, Genoa fault and Tahoe-Sierra frontal fault are in the vicinity of the City’s boundary. The City is therefore situated within an area of high potential seismic activity, and so the fault systems within and around the City have the potential to produce earthquakes that could significantly impact the City. A high-magnitude earthquake on one of these faults could cause moderate to high ground shaking in the City. Figure 4-12 below is an earthquake shaking map for the City of South Lake Tahoe that is based on the two percent probability of occurrence in 50 years, per the USGS analyses of nearby faults. This probability of occurrence map represents a more worst-case shaking scenario and shows that the City will experience strong ground shaking (90% - 100% g), which has the potential to be damaging. 554
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Faulting is the displacement that reaches the earth’s surface during a slip along a fault. Surface faulting commonly occurs with shallow earthquakes. California is a seismically active area with numerous faults throughout the region. An active fault is defined by the California Geological Survey (CGS) as a fault that has had surface rupture or displacement within the last 11,000 years (Holocene times). This does not mean, however, that faults having no evidence of surface displacement within the last 11,000 years are necessarily inactive. Potentially active faults are those that have shown displacement within the last 1.8 million years (Quaternary period) but have not moved within the Holocene times. Any fault older than Pleistocene (>1.8 million years) is considered inactive and dormant.

As shown in Figure 4-13 and also according to the USGS Earthquake Hazards data, there are several earthquake faults classified as Quaternary (those which are recognized at the surface and which have shown activity in the past 1.8 million years, or during the geologic Quaternary epoch) within the City’s boundary and in the vicinity of the City. Both the Tahoe Valley fault zone and East Tahoe fault go through the City. In addition, although not necessarily going through the City Planning Area, the West TahoeDollar Point fault zone, Genoa fault, Tahoe-Sierra frontal fault zone are in the vicinity of the City.

The faults illustrated in Figure 4-13 are summarized below:
• West Tahoe-Dollar Point fault zone to the west of the City; • Tahoe-Sierra frontal fault zone to the northwest of the City; • One part of the Tahoe Valley fault zone goes through the west of the City, another part of the Tahoe Valley fault zone bisects the City and the third part of Tahoe Valley fault zone goes through the east of the City;
• East Tahoe fault going through the east of the City;
• Genoa fault to the east of the City’s boundary.
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Liquefaction if the process by which water-saturated sediment temporarily loses strength and acts as a fluid. Ground shaking a result of an earthquake can cause this effect. Building and road foundations lose load-bearing strength and may sink into what was previously solid ground. Hazardous materials can also be released and cause damage to the environment and people.

The National Earthquake Hazard Reduction Program (NEHRP) creates maps based on soil characteristics to identify locations subject to liquefaction. NEHRP soil types help define locations that can be impacted by an earthquake. The NEHRP soil maps and liquefaction spatial data were not available for the City Planning Area. Sandy and loosely compacted soils in areas with shallow groundwater (30 ft deep or less) are more prone to liquefaction, typically found in floodplains and potentially in areas of the shores of Lake Tahoe. Section 4.3.5 discusses the SEZs in the City’s Planning Area and this classification depicts shallow groundwater and information on alluvial deposits, which is another indication of areas in the City prone to water-saturation and liquefaction.

Location
Significant – As mentioned in the City’s 2008 HMP, earthquakes can occur at any time. Earthquake location is also based on its focal depth and the position of its epicenter. The focal depth of an earthquake is the depth from the earth’s surface to the region where an earthquake originates (focus or hypocenter). The epicenter of an earthquake is the point on the earth’s surface directly above the focus area or hypocenter. The City is located along the border of California and Nevada, two of the most geologically active, earthquake-prone states in the United States. Here, two of the earth's tectonic plates collide. The North American plate slowly moves westward, colliding with the Pacific plate. Simultaneously, the Pacific plate migrates north and westward. As it migrates, the Pacific plate pulls at the North American plate to follow suit. This tensional force stretches the earth's crust, causing a system of north and south fault structural systems all along the boundary between the two tectonic plates. As a result of this tensional stress, ranges of tilted fault block mountain ranges are formed in response to this faulted crustal structure.

The City’s earthquake-prone geology is resultant from this tectonic stretching. The City is considered to be part of the Basin and Range province of the western United States. Here, the earth's crust has been stretched up to 100% of its original width. The entire region has been subjected to the extension that thinned and cracked the crust as it was pulled apart, creating large faults. Earthquakes occur as part of these huge and faulted mountain ranges. Moreover, virtually the entirety of the City lies within the Sierra Nevada range of mountains. This mountain range formed less than five million years ago. Through a combination of uplift of the Sierran block and down dropping of the area to the east, the Sierra rose upward, rising far more steeply to the east than the west. The entire Sierra Nevada can be thought of as an enormous and tilted fault block with a long, gentle slope westward to California's Central Valley and a steep eastern slope. The City sits atop the crest of this gigantic and tilted block of granite.

As for the region, Lake Tahoe would not exist today if not for earthquakes and three major fault zones.

Three major fault zones - the West Tahoe Fault between modern-day Emerald Bay and Dollar Point, the Stateline Fault running south from Crystal Bay and the Incline Village Fault running south from Incline Village – formed the Lake Tahoe Basin about 3.5 million years ago. (TAHOE QUARTERLY n.d.) As specified above, both Tahoe Valley fault zone and East Tahoe fault go through the City. In addition, West Tahoe-Dollar Point fault zone, Genoa fault and Tahoe-Sierra frontal fault zone are also in the vicinity of the City’s boundary. A recent study published on Geosphere explains that Tahoe-Sierra frontal fault zone is the active structural boundary of the Sierra Nevada microplate and that Tahoe-Sierra frontal fault zone has a higher rate of slip than West Tahoe-Dollar Point fault zone. The study also indicates that both 558
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Tahoe-Sierra frontal Fault Zone. The Tahoe-Sierra frontal fault zone, whose trend varies from N26° to 45°W (334–315° AZ), extends over 100 km from near Echo Lakes to the Mohawk Valley fault. A recent USGS publication shows that airborne Lidar analysis and geochronology of faulted glacial moraines in the Tahoe-Sierra frontal fault zone reveal substantial seismic hazards in the Lake Tahoe region. (James et al. 2012, 1087-1101)
Genoa Fault. The Genoa Fault, which extends along the eastern front of the Carson Range south of Carson City, Nevada into the southern reaches of EI Dorado, has been identified as responsible for two large earthquakes measuring in the magnitude seven (7) range during the past 1,000 years (City of SLT 2008 HMP)
Figure 4-13 shows the historical earthquake epicenters that are within the vicinity of the City’s boundary.

In the last over 200 years, the epicenters of several high-magnitude earthquakes were within the vicinity of the City, including one 6.3 earthquake that happened in 1994 and has its epicenter in southeast Douglas County, Nevada. This 6.3 earthquake “broke dishes, damaged chimneys and shook rocks onto highways, but caused no injuries”, as reported by Los Angeles Times on September 13, 1994. Figure 4-13 also shows Alquist-Priolo fault traces and fault hazard zones that are near the City. Alquist-Priolo earthquake fault zones are regulatory zones surrounding the surface traces of active faults in California. (A trace is a line on the earth's surface defining a fault.) Wherever an active fault exists, if it has the potential for surface rupture, a structure for human occupancy cannot be placed over the fault and must be a minimum distance from the fault (generally fifty feet). (California Department of Conservation, n.d.).

Earthquakes in the Tahoe Basin could also result in lake seiche hazards. Refer to Section 4.3.5, Flood for a discussion on seiche hazards within the City’s Planning Area. 559
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Catastrophic – Extent (meaning the severity of an earthquake) refers to the amount of energy released during an earthquake and is usually expressed in terms of intensity or magnitude. These metrics are measured directly from the earthquake as recorded on seismographs.

Intensity represents the observed effects of ground shaking at any specified location, and earthquake shaking decreases with distance from the earthquake epicenter. Intensity is an expression of the amount of shaking at any given location on the ground surface based on felt or observed effects. Seismic shaking is typically the greatest cause of losses to structures during earthquakes. Intensity is measured with the Modified Mercalli Intensity (MMI) scale.

Table 4-14 below compares magnitude and the felt effects associated with the MMI scale. The MMI scale is represented visually using shake maps, which show the expected ground shaking at any given location produced by an earthquake with a specified magnitude and epicenter. Damage typically occurs in MMI of VII or above. Based on Figure 4-13 the majority of the City is found in areas where spectral acceleration is expected to surpass 70 percent g (or gravitational velocity); this means that there is a high probability of the City experiencing strong seismic movements in the next few decades.

Table 4-14 Magnitude and Mercalli Intensity Scale Measurements and Associated Characteristics
Magnitude Mercalli
Intensity
Effects Frequency
Less than 2.0 I Micro-earthquakes, not felt or rarely felt; recorded by seismographs.

Continual

2.0-2.9 I to II Felt slightly by some people; damages to buildings. Over 1M per year

3.0-3.9 II to IV Often felt by people; rarely causes damage; shaking of indoor objects noticeable.

Over 100,000 per year

4.0-4.9 IV to VI Noticeable shaking of indoor objects and rattling noises; felt by most people in the affected area; slightly felt outside; generally, no to minimal damage.
10K to 15K per year

5.0-5.9 VI to VIII Can cause damage of varying severity to poorly constructed buildings; at most, none to slight damage to all other
buildings. Felt by everyone.
1K to 1,500 per year

6.0-6.9 VII to X Damage to a moderate number of well-built structures in populated areas; earthquake-resistant structures survive with slight to moderate damage; poorly designed structures
receive moderate to severe damage; felt in wider areas; up to hundreds of miles/kilometers from the epicenter; strong to violent shaking in epicentral area.
100 to 150 per year

7.0-7.9 VIII< Causes damage to most buildings, some to partially or completely collapse or receive severe damage; welldesigned structures are likely to receive damage; felt across great distances with major damage mostly limited to 250 km from epicenter.
10 to 20 per year

8.0-8.9 VIII< Major damage to buildings, structures likely to be destroyed; will cause moderate to heavy damage to sturdy or
earthquake-resistant buildings; damaging in large areas; felt in extremely large regions.

One per year

9.0 and
Greater
VIII< At or near total destruction - severe damage or collapse to all buildings; heavy damage and shaking extends to distant locations; permanent changes in ground topography.

One per 10-50 years
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Magnitude represents the amount of seismic energy released at the hypocenter of an earthquake and is based on the amplitude of the earthquake waves recorded. Seismologists have developed several magnitude scales; one of the first was the Richter Scale, developed in 1932 by Dr. Charles F. Richter of the California Institute of Technology. The Moment Magnitude Scale (Mw) is the current scale used to quantify the magnitude or strength of the seismic energy released by an earthquake. Table 4-15 summarizes the scale ratings.

Table 4-15 Moment Magnitude Scale (Mw) Ratings
Rating Mw
Great >8.0
Major 7.0 – 7.9
Strong 6.0 – 6.9
Moderate 5.0 – 5.9
Light 4.0 – 4.9
Minor 3.0 – 3.9
Micro <3.0

8.0-8.9 VIII<

9.0 and Greater VIII<
Previous Occurrences
Earthquakes have occurred nearby and within the City in the past (within El Dorado County and adjacent areas).

According to the USGS, a recent earthquake event of a
magnitude of 6.0 shook the area south of Lake Tahoe.

The earthquake's epicenter was in the area around
Walker in Mono County, near the Nevada state line. The
earthquake shook the area south of Lake Tahoe shortly
before 4 p.m. on July 8, 2021 and was reportedly felt as far away as Sacramento and the Bay Area. It was the
largest earthquake in the area since a 6.1 hit in 1994. A section of US 395 was closed temporarily due to
rockslides. Some vehicles were hit by the falling rocks resulted from the rockslides on US 395 and SR 89, but
no injuries were reported. As mentioned above,
although earthquakes can and do occur at any time in
the City and the nearby area, they have not caused the
City any significant damage or mortality so far.

Other recent earthquake events in the area include smaller magnitude earthquakes such as:
• A magnitude 4.8 earthquake with a reported intensity of VI, on June 26, 2005. This event’s epicenter was about eight kilometers north-northwest of Tahoe Vista, which is located on the north shore of Lake Tahoe in Placer County, California. The depth of the event was 2.3 kilometers. • A magnitude 4.2 earthquake with a reported intensity of VI, on May 28, 2021. The epicenter of this incident was about 10 kilometers southeast of Dollar Point, which is a census-designated place in Placer County, along the northwest shore of Lake Tahoe. The depth of the event was seven kilometers. • A magnitude 3.5 earthquake took place on January 1, 2011 and had a reported intensity of III. Its depth was 0.4 kilometer and the epicenter was located two kilometers north-northwest of Mesa Vista, Shortly before 4 p.m. on July 8, 2021, a magnitude of

6.0 shook the area south of Lake Tahoe. The
earthquake's epicenter was in the area around Walker
in Mono County, near the Nevada state line. The
earthquake was reportedly felt as far away as
Sacramento and the Bay Area. A section of US 395 was
closed temporarily due to rockslides. Some vehicles
were hit by the falling rocks resulted from the
rockslides on US 395, as shown in the photo above.

Photo Credit: abc7
562
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Probability of Future Occurrences
Likely – Given the information presented herein as well as recent quake activity history, earthquake hazards are expected to be a likely occurrence in the City as well as in El Dorado County. Faults and seismic activity have played a significant role in shaping the landscape of the Lake Tahoe Region, which includes the City. Scientists estimate the risk of a magnitude-7 quake under Lake Tahoe in the next 50 years to be between 3% and 4%. In addition, with many small faults, the Tahoe Region gets many small earthquakes—ranging from 12,000 to 19,000 quakes registering a year, although large earthquakes have occurred in the region as well in the past. (Tahoetopia n.d.; TAHOE QUARTERLY n.d.) Climate Change Considerations
While climate change is not expected to directly affect earthquake frequency or intensity, it could exacerbate indirect or secondary impacts of earthquakes related to landslides and liquefaction. Climate change would have a “medium” influence on earthquake hazards.

Vulnerability Assessment
Ground shaking is the primary hazard related to earthquake activity. Many factors affect the survivability of structures and systems from earthquake-caused ground motions. These factors include proximity to the fault, the direction of rupture, epicentral location and depth, magnitude, local geologic and soils conditions, types and quality of construction, building configurations and heights, and comparable factors that relate to utility, transportation, and other network systems. Ground motions become structurally damaging when average peak accelerations reach 10 to 15 percent of gravity, average peak velocities reach 8 to 12 centimeters per second, and when the MMI scale is about VII, which is considered to be very strong (general alarm; walls crack; plaster falls).

Fault rupture itself contributes very little to damage unless the structure or system element crosses the active fault. In general, newer construction is more earthquake-resistant than older construction because of improved building codes and enforcement. Manufactured housing is very susceptible to damage because rarely are the foundation systems braced for earthquake motions. Locally-generated earthquake motions, even from very moderate events, tend to be more damaging to smaller buildings, especially those constructed of unreinforced masonry (URM).

Other common impacts from earthquakes include damage to infrastructure and buildings (e.g., crumbling of URM construction, failure of architectural facades, rupturing of underground utilities, and road closures). Earthquakes also frequently trigger secondary hazards, such as dam and levee failures, flooding, and fires that can become disasters themselves.

FEMA’s loss estimation software, Hazus-MH (which originally stood for ‘Hazards U.S.’), was used to analyze the City’s vulnerability to earthquakes, at the census tract level (for six tract units that cover the City). Note that these census tract boundaries do not neatly line up with the City’s boundary, and as such a slightly larger area than that covered in this planning context was necessary to include South Lake Tahoe. Because of these boundary differences, the damage and loss estimates may be slightly exaggerated (given the larger coverage of structures and population). The USGS Earthquake Hazards Program produces ShakeMaps that map ground motion and shaking intensity following significant earthquakes. The USGS also creates Scenario ShakeMaps of hypothetical earthquakes and assumed magnitude on known faults and Probabilistic ShakeMaps based on predicted shaking from all possible earthquakes. The probabilistic maps aggregate scenario map information to make a forecast on future ground motion at any given point that has a given probability of being exceeded in a certain timeframe. 563
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Loss estimates and vulnerability assessment discussions are based on the following subsections: property; people; the local economy; critical facilities and infrastructure; historic, cultural, natural resources; and future development in the Planning Area.

Refer to Section 4.1.1 and FEMA’s Hazus 4.0 Loss Estimation Tool for more information on the Hazus tool and its analysis functions. This methodology was selected to support the vulnerability assessment, as it is a national standard for modeling earthquake loss. To evaluate potential losses associated with earthquake activity in the Planning Area, a Hazus 2,500-year probabilistic scenario was run for the City’s six census tracts, using a magnitude of 7.0 as the parameter (Hazus driving magnitude) that would simulate a strong earthquake. Due to these inputs, this 2,500-year scenario represents more of a worst-case level of shaking that considers multiple faults in the region that has two percent probability in 50 years. Hazus estimates the number of people displaced, the number of buildings damaged and their type (e.g. construction material, occupancy class), the number of causalities, and the damage to transportation systems and utilities (e.g. critical facilities).

A summary of the key losses based on the Hazus earthquake analysis results included the following:
• Total economic loss estimated for the earthquake was $1.92 billion, which includes building losses and lifeline-related losses based on the Hazus inventory for the Planning Area. • Building-related losses, including direct building damages and business interruption losses, totaled $1.91 billion.
• $332.2 million in losses came from income-related losses from wage-related, capital-related, rental properties, and relocation costs, while $1.6 billion came from capital stock losses related to structural, contents-based, and inventory property categories.
• 17 percent of the estimated losses were related to business interruptions. • 8,474 buildings (70 percent of total in the region) would be at least moderately damaged; 1,142 of those buildings would be damaged beyond repair.
• Residential structures made up 66 percent of the total earthquake-induced losses. • $5.95 million in losses are associated with transportation system economic damages and losses (e.g. highways, buses, airport facilities and related infrastructure). • $2.05 million in losses are associated with utility and lifeline system economic damages and losses (e.g. potable water, wastewater, natural gas, oil systems, communications, and related infrastructure). • The mid-day earthquake (2 p.m.) caused the most injuries and casualties: 896 injuries and 70 fatalities. • The model estimates that a total of 360,000 tons of debris will be generated. Brick and Wood structures comprise 34 percent of the total, with the rest being Reinforced Concrete and Steel materials.
• An estimated 1,763 households would be displaced of which 1,139 will seek temporary shelter in public shelters.
• Around 8,937 households are expected to suffer from potable water or electric power losses, or both, on the first day of the earthquake event.
• All 11 essential facilities considered by the Hazus earthquake scenario for the Planning Area (one hospital, six schools, one police station, and three fire stations), will be at least moderately damaged. • Before the earthquake, the region had 111 hospital beds available for use. On the day of the earthquake, the model estimates that only one hospital bed (1 percent) would be available for use by patients already in the hospital and those injured by the earthquake.

Property
Significant earthquakes can cause damages to buildings, private and public property, and other infrastructure. The California Building Code (CBC) was modified several times since 1960, which resulted in 564
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The number of properties at risk is also based on when the majority of development was constructed in the City, which primarily occurred in the 1950s through 1970’s. This construction consisted of mostly residential structures completed before the City adopted the more stringent CBC. The City of South Lake Tahoe adopted the 2019 Edition of the CBC (California Code of Regulations, Title 24, Part 2 [incorporates 2018 Edition of the International Building Code]). Most developments in the City’s Planning Area occurred during the past 50 years prior to when the City enforced the new code requirements. The Hazus earthquake results accounted for the improved seismic codes in the model.

Hazus estimates that 8,474 buildings (70 percent of the total buildings in the region) would be at least moderately damaged, while 1,142 of those buildings would be damaged beyond repair by the earthquake scenario. A majority of the buildings experiencing damage are residential structures, and wood frame construction makes up the majority of building/structure material in the Planning Area’s inventory. Figure 4-15 summarizes the specific estimated damages to buildings based on occupancy and damage category. 565
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With a majority of the buildings in the Planning Area being residential, the Hazus model estimates that over 94 percent of the total losses incurred by this earthquake scenario are single-family homes and other residential categories. The building inventory in the region varies in terms of construction types. A large number of buildings are also constructed of wood materials, though the building inventory includes URM buildings and manufactured housing. These types of wood, masonry, and manufactured housing structures are particularly vulnerable to ground shaking in an earthquake event. Table 4-16 describes the Hazus results of expected building damage by building type. Most buildings/structures found are expected to sustain slight to moderate damages, but over 1,000 are modeled to have complete damage. 566
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People
Hazus estimates the number of people that would be injured or killed by the 2,500-probabilistic earthquake scenario. The causalities are broken down into four severity levels. Level 1 means that injuries occur but do not need hospitalization (i.e. the lowest level, causing the least damages or injuries), through to Level 4, where victims are killed by the earthquake (i.e. the highest, or worst, of the levels). The estimates are also provided for three times of the day which represent the periods of a standard working day when different sectors of the community are likely at their peak occupancy loads (e.g. in business/office settings versus residing at home). As shown in Table 4-17 below, the highest number of injuries and casualties are estimated to occur in the early afternoon (2 p.m.) with the greatest impacts on the commercial and educational sectors when those sector loads are considered to be at their maximum.

The 2 p.m. time has the greatest potential for fatalities, with an estimate of 70, followed by the 5 p.m. scenario which estimates 41 fatalities (more information below).

Some populations in the Planning Area may be more vulnerable to an earthquake event than others. For example, those with mobility issues as well as the elderly may have challenges with evacuating or traveling to a shelter without assistance if they cannot stay in their homes. Other vulnerable populations may be individuals for whom English is not their native language. Of these socially vulnerable populations, according to Section 2.8.3 Disadvantaged Communities, several of these populations are anticipated to reside within the eastern part as well as central and southwestern parts of the City, as well as within older housing that may have been constructed before the seismic code improvements.

According to 2015-2019 ACS estimates, 20.4 percent of citizens that are 18-year-old and older in the City speak a language other than English in their home. These individuals may not receive or understand evacuation information including where shelters are located or where to receive resources to aid in the recovery process. These same individuals and households are designated as socially vulnerable populations, many of which reside in the central, eastern and southwestern areas of the City. Figure 4-16 shows the Hazus report estimates for the total number of households expected to be displaced as a result of the earthquake. The report estimates 1,763 households to be displaced, and of those, 1,139 individuals will be seeking temporary shelter. This does not take into account future population growth or other variables, such as populations increases due to tourism. 567
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Table 4-17 shows the Hazus estimates for total casualties and injuries. 568
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Economy
Earthquakes can have a severe impact on local and regional economies. Impacts can be both direct, such as damages to commercial and residential structures and lifeline facilities, as well as indirect such as 569
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Another secondary or cascading impact an earthquake could have is causing damages to transportation infrastructure that is critical to employees and business activity. Based on the Hazus results, the 2% in 50 years probabilistic scenario could potentially cause a total of $1.92 billion in economic losses. This amount includes 1) building-related losses, which further include income losses ($332.2 million) as well as capital stock losses ($1.6 billion); 2) transportation system losses ($5.95 million); and 3) utility system losses ($2.05 million).

Hazus describes business interruption losses as those losses associated with the inability to operate a business because of the damage sustained by the earthquake and include the temporary living expenses for individuals displaced from their homes.

Hazus estimates the total building-related losses. This includes business interruption losses and direct building losses (the estimated costs to repair or replace the damage caused to buildings and their contents) at $1.9 billion, 17 percent of which are related to business interruption in the region. As shown in Figure 4-17 and Table 4-18 below, the largest loss in this scenario was sustained by residential occupancies, making up 66 percent of total loss. The following figures and tables report the estimate of losses by loss type, occupancy type, and building-related loss.

Figure 4-17 Economic Loss Estimates by Loss Type and Occupancy Type Source: Hazus 4.0
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Critical Facilities and Infrastructure
Large seismic events could have catastrophic effects on the City and surrounding areas, possibly damaging transportation and utility lifelines, bridges, railroads, and other critical facilities and infrastructure. Hazus estimates impacts to essential facilities including hospitals, schools, Emergency Operations Centers (EOCs), police stations, and fire stations. The Hazus analysis also takes into account four hazardous material sites, though zero nuclear power plants and zero military installations fall within the study area.

In addition to economic losses experienced by building-related losses, Hazus estimates the economic losses as a result of transportation and utility lifeline losses and the direct repair cost for each component.

As shown in Table 4-19 and Table 4-20 below it is estimated that $5.95 million will be lost as a result of damages to transportation components and $2.05 million are expected to be lost as a result of utility system damages. Of the $5.95 million, $3.5 million is related to the loss of the City’s airport. 571
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According to the earthquake analysis, there is one hospital with a total capacity of 111 beds, six schools, zero emergency operations facility, one police station, and three fire stations in the study area. Barton Medical Hospital has 63 patient beds, 48 residential beds, and a skilled nursing facility (Barton 2021).

Hazus estimates that seven of these essential facilities are expected to suffer moderate damage. With regards to transportation systems, four will suffer at least moderate damage, and none will suffer complete damage. However, only one of the utility system facilities will suffer at least moderate damage, but zero of these types of facilities will suffer complete damage. Table 4-21, Table 4-22, and Table 4-23 summarize the expected damages generated by the Hazus scenario for each type of transportation system and utility system, including pipelines in the area. 573
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Source: Hazus 4.0
Table 4-23 Expected Utility System Pipeline Damage (Site Specific) Source: Hazus 4.0
Historic, Cultural, and Natural Resources
An earthquake in the City’s Planning Area or the surrounding region could cause cascading (secondary) effects, including dam or pipeline failure that would impact the natural environment in different ways, depending on the extent of the cascading hazard. For example, earthquake-induced landslides or debris flows could significantly damage habitat and re-route streams and waterways, causing water quality impacts. Other types of ground deformation could also result.

Magnitude 7.2 Deterministic ShakeMap Earthquake Scenario A second Hazus-based earthquake scenario was modeled for the Planning Area using census tract units and was based on a deterministic model. A deterministic scenario relies on seismic data to predict the outcome of a specific earthquake event. This deterministic scenario used USGS-provided ShakeMap datasets to model what a magnitude 7.2 earthquake of the West Tahoe Fault would generate in terms of damages and losses for the chosen area of interest (i.e. the City Planning Area). This fault was selected because it is known to have caused seismic activity and pose a risk to South Lake Tahoe and nearby communities. The M7.2 ShakeMap scenario datasets imported into Hazus 4.0 include four USGS-provided key data layers in the spatial format: peak ground velocity, peak ground acceleration, peak spectral acceleration for 0.3 seconds (0.3 % g, or gravitational velocity), and peak ground acceleration for 1.0 seconds (1.0 % g). The epicenter of this USGS modeled scenario is located at latitude 39.01 North and 575
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Figure 4-18 USGS Generated ShakeMap Earthquake Scenario for the West Tahoe Fault Source: USGS 2016, Worden et al 2012
For more information on the USGS generated ShakeMap scenarios, modeling criteria, manual information, and overall catalog of available data refer to the USGS Earthquake Hazards Program ShakeMap information page.
576
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-80 Loss estimates and vulnerability assessment were completed based on the following subsections, similar to the previous scenario: property; people; the local economy; critical facilities and infrastructure; historic, cultural, natural resources; and future development of the Planning Area. The total losses by census tract from this M7.2 scenario are shown in Figure 4-18 and summarized in Table 4-24 below. Refer to Section

4.1.1 and FEMA’s Hazus 4.0 Loss Estimation Tool for more information on the Hazus tool and its analysis functions. As stated in the previous section, Hazus is a loss estimation tool that derives totals on the number of people displaced, the number of buildings damaged and their type (e.g. construction material, occupancy class), the number of causalities, and the damage to transportation systems and utilities (e.g. critical facilities) given the input parameters, scenario type, and region/area of interest.

Table 4-24 Deterministic M7.2 Earthquake Scenario Loss Estimations for South Lake Tahoe’s Census Tracts
Type of Impact Impacts to Planning Area
Total Buildings Damaged Slight: 3,518
Moderate: 4,273
Extensive: 1,887
Complete: 782
Building and Income-Related Losses $ 1,415.86 million
60 % of damage related to residential structures
18 % of loss due to business interruption
Total Economic Losses (Includes building, income,
and lifeline/critical facility losses)
$ 1,422.19 million
Casualties (Based on a 2 a.m. time of occurrence) Without requiring hospitalization: 134 Requiring hospitalization: 31
Life threatening: 4
Fatalities: 7
Casualties (Based on a 2 p.m. time of occurrence) Without requiring hospitalization: 571 Requiring hospitalization: 181
Life threatening: 31
Fatalities: 61
Casualties (Based on a 5 p.m. time of occurrence) Without requiring hospitalization: 359 Requiring hospitalization: 113
Life threatening: 26
Fatalities: 37
Damage to Transportation Systems 1 moderate damage worth $0.8 million in damages to bridges
1 moderate damage worth $2.4 million in damages to airport facilities
2 moderate damage worth $1.5 million in damages to bus
facilities
0 damage to light rail
0 damage to ferry and port facilities
Damage to Essential Facilities 11 facilities moderate damages to schools, police stations, fire stations, EOCs, or hospitals
Damage to Utility Systems 1 communication facility will receive at least moderate damage.

Potable water pipeline breaks: 51
Wastewater pipeline breaks: 26
Natural gas pipeline breaks: 0
Oil pipeline breaks: 0
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Households without Power/Water Service (Based
on 8,937 total households)
Power loss, Day 1: 6,075
Power loss, Day 3: 3,533
Power loss, Day 7: 1,319
Power loss, Day 30: 231
Power loss, Day 90: 9
Water loss, Day 1: 3,127
Water loss, Day 3: 0
Water loss, Day 7: 0
Water loss, Day 30: 0
Water loss, Day 90: 0
Displaced Households 1,206
Persons Seeking Temporary Shelter 745
Debris Generation 286,000 tons
Source: Hazus 4.0, USGS ShakeMap M7.2 Scenario for West Tahoe Fault Property
The Hazus results for this M7.2 scenario indicate 6,942 buildings will be at least moderately damaged. This is over 57 percent of the total buildings in the region. However, approximately 782 buildings will be completely destroyed. The majority of these at least moderately damaged buildings are residential, followed by commercial buildings and lastly industrial buildings. With a majority of the buildings in the Planning Area being residential, the Hazus model estimates that over 94 percent of the total losses incurred by this earthquake scenario are single-family homes and other residential categories. Table 4-25 provides a detailed breakdown of these expected building damages based on the occupancy types.

Table 4-25 Expected M7.2 Earthquake Scenario Building Damages by Occupancy Type Source: Hazus 4.0, USGS ShakeMap M7.2 Scenario for West Tahoe Fault The building inventory in the region varies in terms of construction types. A large number of buildings are also of wood materials, though the building inventory also includes unreinforced masonry buildings and manufactured housing. These types of wood, masonry, and manufactured housing structures are particularly vulnerable to ground shaking in an earthquake event. Most buildings/structures found are expected to sustain slight to moderate damages, with the wood and manufactured housing materials making up the largest percentages of the damaged building materials category. 578
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Hazus estimates the number of people that would be injured or killed by the M7.2 ShakeMap earthquake scenario. The causalities are broken down into four severity levels as described in the previous Hazus model summary (2,500-year probabilistic scenario). The estimates are provided for three times of the day which represent the periods of a standard working day when different sectors of the community are likely at their peak occupancy loads. The highest number of injuries and casualties are estimated to occur in the afternoon (2 p.m.) with the greatest impacts on commercial sectors followed by educational and industrial as these sector loads are considered to be at their maximum in the late afternoon/early evening times.

This 2 p.m. time has the greatest potential for fatalities, with an estimate of 61, followed by the 5 p.m. scenario which estimates 37 fatalities.

Some populations in the Planning Area may be more vulnerable to an earthquake event than others. Most vulnerable individuals who may not receive or understand evacuation information including where shelters are located or where to receive resources to aid in the recovery process would be at high risk of earthquakes. The Hazus report estimates 1,206 households to be displaced, and of those, 745 individuals will be seeking temporary shelter. It should be noted that this does not take into account future population growth or any other variables such as seasonal or weekend tourism to the region. An earthquake would have a disproportionate impact on socially vulnerable populations residing in the downtown area of South Lake Tahoe.

Economy
Earthquakes can have a severe impact on local and regional economies as previously discussed in the 2,500-year probabilistic Hazus analysis subsection. Based on this Hazus M7.2 scenario, the modeled earthquake could potentially cause a total of $1,422.19 million in economic losses. This amount includes 1) building-related losses, which further include income losses ($259.1 million) as well as capital stock losses ($1,156.76 million); 2) transportation system losses ($4.74 million); and 3) utility system losses ($1.59 million).

Another secondary impact of an earthquake is business disruption and the resulting economic loss as a result of that disruption. Hazus describes business interruption losses as those losses associated with the inability to operate a business because of the damage sustained by the earthquake and include the temporary living expenses for individuals displaced from their homes. Of the total $1,415.86 million in building-related losses, 18 percent are related to business interruptions in the region.

In addition to economic losses experienced by building-related losses, Hazus estimates the economic losses as a result of transportation and utility lifeline losses and the direct repair cost for each component.

It is estimated that $4.74 million will be lost as a result of damages to transportation components while almost $1.59 million are expected to be lost as a result of utility system damages from the M7.2 modeled ShakeMap scenario.

Critical Facilities and Infrastructure
Large seismic events could have catastrophic effects on the City and surrounding areas, possibly damaging transportation and utility lifelines, bridges, railroads, and other critical facilities and infrastructure. Hazus estimates impacts to essential facilities including hospitals, schools, EOCs, police stations, and fire stations. The Hazus analysis also takes into account four hazardous material sites. No nuclear power plants or military installations fall within the study area.

According to the earthquake analysis, there is one (1) hospital with a total capacity of 111 beds, six (6) schools, zero (0) emergency operations facility, one (1) police station, and three (3) fire stations in the study area. This M7.2 Hazus earthquake scenario estimates that all of these essential facilities are expected 579
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The only utility systems or structures that are expected to suffer site-specific damages are shown in Table 4-26 and Table 4-27. These damage estimates are also summarized in the overall scenario summary table at the beginning of the section (Table 4-24).

Table 4-26 Expected Utility System Pipeline Damage (Site Specific) Source: Hazus 4.0, USGS ShakeMap M7.2 Scenario for Hayward-Rodgers Creek Table 4-27 Expected Potable Water and Electric Power System Performance Source: Hazus 4.0, USGS ShakeMap M7.2 Scenario for Hayward-Rodgers Creek Historic, Cultural, and Natural Resources
The same general impacts, potential risk, and cascading or secondary issues discussed for the 2,500-year probabilistic scenarios would apply to the Planning Area’s historic, cultural, and natural resources based on this M7.2 modeled ShakeMap scenario which uses the West Tahoe faults.

Future Development
Each Hazus scenario only estimates damage and causalities for existing building inventory and populations and does not take into account future development plans. The City also needs to meet its General Plan Safety Element goal and objectives and ensure that risk reduction in the community is taken into account, particularly when dealing with earthquakes and other geologic hazards. The South Lake Tahoe General Plan of 2030 (adopted in 2011) and its Health and Safety Element establish standards and requirements for the protection from geologic and seismic hazards. Building and development will also be regulated through the current 2019 CBC and International Building Code (IBC) building standards.

Risk Summary
• Earthquakes and seismic activity are expected to have a probability of occasional occurrence in the future, given the local seismic conditions, history, and input from the City. • Several Quaternary earthquake faults traverse the City or are within the vicinity, including Tahoe Valley fault, East Tahoe fault, West Tahoe-Dollar Point fault, Genoa fault, and Tahoe-Sierra frontal fault. • The 2500-year probabilistic earthquake scenario Hazus model would cause $1.92 billion in total economic losses, including $5.95 million in losses to transportation systems and $2.05 million in damages and losses to utility lifelines. Most losses would affect residential buildings and most households in the City would be impacted by loss of power and potable water. 580
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-84 • The deterministic magnitude 7.2 ShakeMap scenario that takes into account the West Tahoe fault would cause $1,422.19 million in total economic losses, including $4.74 million of losses to transportation systems and $1.59 million in damages and losses to utility lifelines. Most losses would affect residential buildings most households would be impacted by the loss of power and potable water.
• The City has a unique risk potential to a lake tsunami or seiche due to earthquake ground shaking and landslides or rockfalls that may cause displacement in Lake Tahoe. The areas along the City’s waterways and SEZs may also have a high potential for liquefaction that deserves future investigation. • The overall risk significance of earthquake hazards to the City is High.

4.3.5 Flood
Hazard Description
Floods are among the most frequent and costly natural disasters in terms of human hardship and economic loss. Flooding is usually the result of, or often exacerbated by, weather events. Floods can cause substantial damage to structures, landscapes, and utilities as well as life safety issues. Certain health hazards are also common to flood events; standing water and wet materials in structures can become breeding grounds for microorganisms such as bacteria, mold, and viruses. Standing water or affected infrastructure can, in turn, cause disease, trigger allergic reactions, and damage materials long after the flood. When floodwaters contain sewage or decaying animal carcasses, infectious disease also becomes a concern. Direct impacts such as drowning can be limited with adequate warning and public education about what to do during floods. Where flooding occurs in populated areas, warning and evacuation will be of critical importance to reduce life and safety impacts.

Floodplains are defined as the areas immediately adjacent to a channel from a river, stream, or other waterways. Floodplains are illustrated on inundation maps, which show areas of potential flooding and water depths. In its common usage and based on FEMA guidelines, the floodplain most often refers to the area that is inundated by the 100-year flood, or the flood that has a one percent chance in any given year of being equaled or exceeded. The 100-year flood is the national minimum standard to which communities regulate their floodplains through the FEMA National Flood Insurance Program (NFIP). The 500-year flood is the flood that has a 0.2 percent chance of being equaled or exceeded in any given year.

A 500-year flood event would be slightly deeper and cover a greater area than a 100-year flood event.

The potential for flooding can change and increase through various land use changes and changes to the land surface, which then may result in a change to the floodplain. A change in environment can create localized flooding problems inside and outside of natural floodplains by altering or confining natural drainage channels. These changes are most often created by human activity.

The City of South Lake Tahoe is susceptible to various types of flood events as described below. • Wet-Mantle and Rain-on-Snow Flooding - Characteristically, wet-mantle and rain-on-snow flooding develops when warm rains fall on already saturated ground. Particularly devastating flooding events happen when heavy snows precede warmer rain events, causing the mantle of snow to melt and run off in conjunction with the rain. The City of South Lake Tahoe has a well-chronicled history of flooding dating to the 1850s. The earliest flood of record occurred in December 1852 and was a precursor to the type of wet-mantle and rain-on-snow flooding characteristic to the Carson River watershed. As described in one historical journal, the storms began "with a heavy wet snow, which lasted for two days and left a three-foot snow depth across Carson Valley. Beginning with the storm's third day, the snow typically turned to a relatively warm rain, which lasted another four days, until December 30. By that time, the snow accumulation had completely melted and run off, along with 581
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-85 great quantities of rainwater." Most of the substantial flood events on the historical record occurred in this fashion. (2008 HMP).
• Dry-Mantle Flooding – Dry-mantle flood events are a result of violent summer thunderstorms and are more localized in nature. Dry-mantle flooding is not widespread, as in the case of wet-mantle and rain-on-snow events. However, this thunderstorm-related flooding can be a major concern, as severe local rain and hail can create conditions for flash flooding and a considerable threat to life and property.
• Localized Flooding – Flash flooding describes localized floods of great volume and short duration.

This type of flood usually results from a heavy rainfall in a relatively small drainage area. Flash floods often require immediate evacuation. Related to this type of flooding is also localized flooding, which is often caused by flash flooding, severe weather, or an unusual amount of rainfall. Flooding from these intense weather events occurs in areas experiencing an increase in runoff from impervious surfaces associated with development and urbanization as well as inadequate storm drainage systems. As mentioned above, dry-mantle flooding also introduces localized/flash flooding. • Dam or Levee Failure Flooding – Potential inundation caused by failure or mis-operation of one or more upstream dams or water control structures such as dams could also impose some threat on the City’s residents and real and personal property. The City’s 2011 General Plan Health and Safety Element noted the concern about the potential for failures of the Echo Lake Dam and a gravel dam located at Echo Lake. Dam failure is addressed in more detail under Section 4.3.2 Dam Incidents. • Riverine Flooding - Riverine flooding, defined as the condition when a watercourse (e.g. river or channel) exceeds its “bank-full” capacity, generally occurs as a result of prolonged rainfall, or rainfall that is combined with already saturated soils from previous rain events. This type of flood occurs in river systems whose tributaries may drain large geographic areas and include one or more independent river basins. The onset and duration of riverine floods may vary from a few hours to many days. Factors that directly affect the amount of flood runoff include precipitation amount, intensity and distribution, the amount of soil moisture, seasonal variation in vegetation, snow depth, and water resistance of the surface due to urbanization.

Flooding of various types may occur anywhere within the City’s Planning Area. Details on local water features, watersheds, and flood control structures and systems are provided below.

Location
Significant – The City of South Lake Tahoe is primarily located within the General Creek-Frontal Lake Tahoe, Upper Truckee River-Frontal Lake Tahoe and Marlette Lake-Frontal Lake Tahoe watersheds (under Hydrologic Unit Codes 1605010104, 1605010103 and 1605010102 respectively). These three watersheds are all parts of the greater Lake Tahoe watershed (Hydrologic Unit Code 16050101; to distinguish, there is also Lake Tahoe with a HUC10 Code as 1605010105, which is shown in Figure 4-19).

The main waterways in the City include the Upper Truckee River and Trout Creek. Upper Truckee River and Trout Creek are the two largest watersheds in the Tahoe Watershed. They also meet within the City’s Planning Area. The Upper Truckee River has a drainage area of approximately 56.5 square miles, and its main channel length is 21.4 miles. The Trout Creek watershed is 41.2 square miles, and its main channel is

12.1 miles long. Although the Trout Creek watershed is of comparable size to that of the Upper Truckee River, it typically produces lower peak flows as a result of watershed shape, slope, and elevation factors.

Other smaller streams also flow through the City, including Bijou Creek, Bijou Park Creek, Keller Creek, Little Heavenly Creek, and Stateline Creek, most of which are ephemeral. (City of South Lake Tahoe 2011) The City of South Lake Tahoe is located entirely within the mountainous Sierra Nevada. The drainages that run from the Sierra Nevada traverse through high-relief and deeply-cut river canyons with only occasional level areas that might be termed floodplains, and eventually find their way to Lake Tahoe. There are miles 582
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-86 of drainage within the City of South Lake Tahoe. There are over 276 square miles of slope drainages from EI Dorado county and a small northern section of Alpine County, which drain into Lake Tahoe.

Tremendous amounts of water can be gravitationally fed through these river canyons with 63 tributaries emptying in Lake Tahoe and only one river the Truckee River emptying out. The City of South Lake Tahoe therefore has a long history of flood events. (City of South Lake Tahoe 2008) Lake Tahoe Watershed (Hydrologic Unit Code [HUC] 16050101) – Lake Tahoe is one of the world’s largest, deepest, and clearest mountain lakes—22 miles long, 11 miles wide and in a 501-square-mile watershed. The communities surrounding it depend on the protection of its natural beauty and yearround recreational opportunities. The U.S. Forest Service and state agencies manage nearly 85% of the watershed’s land. From the 1860s through the early 1900s, the lake’s watershed lands were extensively logged, and the second-growth forest that has grown over the past century is denser, making it vulnerable to wildfires. Since 1950, the development of homes, recreational facilities and urban infrastructure has increased the amounts of sediment entering the lake, causing algae growth and reducing the lake’s clarity. Since the early 1970s, wastewater has been treated and pumped out of Lake Tahoe’s watershed, preventing a major source of nutrients. In addition to being a scenic and ecological treasure, the Lake Tahoe watershed is one of the outstanding recreational resources of the United States.

It is recognized nationally and globally as a natural resource of special significance, and the lake is designated an "Outstanding National Resource Water" under the Clean Water Act. (U.S. EPA 2021) 583
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-87 Figure 4-19 Local Watersheds in the Vicinity of the City of South Lake Tahoe 584
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-88 Major drainage features within the Planning Area or managed by the City of South Lake Tahoe include:
• Upper Truckee River
• Trout Creek
• Bijou Creek
• Bijou Park Creek
• Keller Creek
• Heavenly Valley Creek
• Sawmill Creek
• Angora Creek
• Little Heavenly Creek
• Stateline Creek
• Meyers Creek
• Other small and unnamed tributaries in the General Creek-Frontal Lake Tahoe, Upper Truckee RiverFrontal Lake Tahoe and Marlette Lake-Frontal Lake Tahoe watersheds • City and County stormwater drainage facilities
• City water weir
• City pumps, tanks, lift, ditches, and
• Other water structures/stations
Floodplain Mapping and Studies
FEMA established standards for floodplain mapping studies as part of the NFIP (FEMA 2019). The NFIP makes flood insurance available to property owners in participating communities adopting FEMAapproved local floodplain studies, maps, and regulations. Floodplain studies that may be approved by FEMA include federally funded studies; studies developed by state, city, and regional public agencies; and technical studies generated by private interests as part of property annexation and land development efforts. Such studies may include entire stream reaches or limited stream sections depending on the nature and scope of a study. A general overview of floodplain mapping and related components is provided in the following paragraphs.

Flood Insurance Study (FIS) - The FIS develops flood-risk data for various areas of a community that are used to establish flood insurance rates and assist the community in its efforts to promote sound floodplain management. The latest FIS applicable to the City of South Lake Tahoe was included in a onevolume report along with other incorporated jurisdictions and unincorporated areas studied in El Dorado County; this recent report was last revised April 3, 2021.

Flood Insurance Rate Map (FIRM) - The FIRM is designed for flood insurance and floodplain management applications. For flood insurance, the FIRM designates flood insurance rate zones to assign premium rates for flood insurance policies. The designated flood zones are based on flood risk in the area.

For floodplain management, the FIRM delineates 100- and 500-year floodplains, floodways, and the locations of selected cross sections used in the hydrology and hydraulic analyses and local floodplain regulations. Land areas that are high risk within the 100-year floodplain (meaning they have a one percent annual chance of flooding), are called SFHAs and are mapped as A or AE zones. The difference between A and AE zones is the level of detail in analysis and mapping so that A zones are more general while AE zones contain additional details and also display Base Flood Elevations, or BFEs. In communities that participate in the NFIP, mandatory flood insurance purchase requirements apply to Zones A and AE (i.e., those areas subject to a 100-year flood event).

The City of South Lake Tahoe FIRMs, as with most portions of California and larger developments across the U.S., have been replaced by new digital flood insurance rate maps (or DFIRMs) as part of FEMA’s Risk 585
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-89 Map and Map Modernization programs. DFIRMs and related datasets (e.g. cross sections used in floodplain studies and analyses, BFEs, etc.) are now delivered via National Flood Hazard Layer (NFHL) GIS databases, accessible for free online at FEMA’s Flood Map Service Center site.

These digital DFIRMs in the NFHL achieve the following purposes:
• Incorporate the latest flood study updates (LOMRs and LOMAs) • Utilize community supplied data
• Verify the currency of the floodplains and refit them to community supplied base maps and base data • Upgrade the FIRMs to a GIS database format to set the stage for future updates and to enable manipulation, storage, and support for GIS analyses and other digital applications • Solicit community participation
The most current DFIRMs for the City of South Lake Tahoe and other jurisdictions or unincorporated areas within El Dorado County are included in the County’s NFHL database. The latest effective date for studies in the County is April 3, 2012. The spatial features available in this NFHL database, such as floodplains, were used for the analyses and mapping in this plan as they relate to flooding hazards.

Letter of Map Revision (LOMR) and Letter of Map Amendment (LOMA) - LOMRs and LOMAs represent separate floodplain studies dealing with individual properties or limited stream segments that update the FIS and FIRM data (as revisions or amendments) between periodic FEMA publications of the FIS and FIRM products.

Major Sources of Flooding
As mentioned above, most of the substantial flood events on the historical record that occurred in the City are wet-mantle and rain-on-snow flooding.

General rainfall floods, primarily associated with seasonal storms and thunderstorms, can occur in the City during winter and spring months. This type of flood results from prolonged heavy rainfall over tributary areas and is characterized by high peak flows of moderate duration. Flooding is more severe when antecedent rain has resulted in saturated ground conditions.

In the more urbanized areas of South Lake Tahoe, flood problems intensify because the immediate areas are developed and contain mostly impervious surfaces such as roads and paved structures. Because of this, the nearby open land available to absorb rainfall and runoff is often limited or difficult to access naturally. In other words, the decrease in the amount of open land that can absorb precipitation increases the volume of water that must be carried away by waterways and developed infrastructure, causing localized flash flooding and stormwater issues.

What are flood zones?
Flood zones are geographic areas on a flood map that indicate flood risk. Zones are determined by assessing the expected height of a flood that has a 1 percent chance of occurring in any given year (“100-year flood”), as well as potential wave heights, the distance from the nearest water body, and the ground elevation. While there is only a 1 percent chance of a flood of such magnitude to occur every year, there is a 26 percent chance of such a flood to occur over the lifecycle of a 30-year mortgage.

Source: Wetlands Watch 2019
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-90 The latest FEMA NFHL data indicate that 100- and 500-year floodplains are predominantly located along Upper Truckee River, which flows through the City from south to north. The floodplains would include Lake Tahoe Airport. Other flooding areas cover Lake Christopher. Most of the floodplains are also along the waterways in the City as well as the SOI boundary. There are flooding areas that cover portions of Highway 89 as well as segments of Highway 50. (See Figure 4-20). Portions of the Lake Valley and Tahoe Valley neighborhoods are located in 100-year flood zones, due to their location along the Upper Truckee River. Areas of 500-year flood risk are located primarily at the confluence of the Upper Truckee River, Meyers Creek, and Angora Creek (City of South Lake Tahoe 2011). Specific areas within the Tahoe Valley neighborhood (e.g., State Streets) at risk include the residences along Michael Drive, portions of California Avenue, Montezuma Drive, Colorado Avenue, and a portion of Dover Drive.

The City of South Lake Tahoe joined the NFIP on July 3, 1978 and adopted their Floodplain Management Ordinance in 1997, which was updated 2001. The City’s Floodplain Management Ordinance provides direction for new and existing developments located within SFHAs. The primary goal of this ordinance is to reduce future flood damage through the implementation of building techniques that minimize the potential loss of life and property due to development in floodplains. It references the more restrictive floodplain development standards found in the TRPA’s Regional Plan and the Lahontan Regional Water Quality Control Board’s (RWQCB) Basin Plan. Chapter 35.4 of the TRPA Code of Ordinances also limits development in the 100-year floodplain. The Lahontan RWQCB’s Basin Plan ordinances contain prohibitions and exemption criteria that apply to projects in the floodplain except for residential projects.

Where the City’s Floodplain Management Ordinance, TRPA Code of Ordinances, and Basin Plan conflict or overlap, the more stringent restrictions prevail. The City, in cooperation with FEMA’s NFIP, has also completed a re-study of the 1978 FIRM and has been revised as of April 3, 2012. The City’s floodplains fall in Zone AE and Zone X, as shown in Figure 4-20.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-91 Figure 4-20 FEMA SFHAs for the 1% and 0.2% Annual Chance Flood Events in the City 588
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Damage caused by flooding is restricted to the wetland and meadows of the City. Consequently, the amount of damages inflicted upon residents and real and personal property are limited to a relatively small area of the City. In contrast though, flash flooding resultant from summer thunderstorms could happen anywhere within the City, but not nearly at the level of a spring flood event (wet-mantle/rain-onsnow flooding). (2008 HMP).

Stream Environment Zones (SEZ)
SEZ is a term unique to the Tahoe Basin and encompasses more than just wetlands. SEZ was developed by TRPA to denote perennial, intermittent and ephemeral streams and drainages, as well as marshes and meadows and other areas of near-surface water influence in the Tahoe Basin. SEZs generally possess the following characteristics: riparian or hydric (wet site) vegetation; alluvial, hydric soils; and the presence of surface water or near-surface groundwater at least part of the year. The TRPA defines an SEZ as generally an areas that owes its biological and physical characteristics to the presence of surface water or groundwater. SEZs, among numerous other functions convey surface runoff from upland areas to water sources and tributaries to Lake Tahoe.

While SEZs may only make up 5% of the land area in the Basin, they provide key habitat for 84% of the 250 wildlife species in the Basin and can help reduce sediment and nutrient runoff concentrations by 70- 90%. In addition to these enormous resource benefits, SEZs can also provide dispersed recreation opportunities, scenic open space, flood flow capacity, and buffers within urban areas. Given these multiple resource benefits that SEZs provide, the California Tahoe Conservancy and other partnering agencies and organizations find it essential to preserve and restore them. (Tahoe Conservancy n.d.). Figure 4-21 below shows the SEZs within and around the City of South Lake Tahoe.

Lake Seiche
A tsunami is a wave caused by an underwater earthquake, landslide, or volcanic eruption. A seiche is a rhythmic motion of water in a partially or completely landlocked water board caused by landslides or earthquake-induced ground shaking. The City’s Planning Area is located immediately adjacent to Lake Tahoe, which could be impacted by a lake seiche. Several of the tributaries feeding into Lake Tahoe could be subject to flooding due to a lake seiche in the event of a major landslide or earthquake given the Planning Area is prone to seismic hazards due to active faults in the region. According to the City’s 2010 General Plan Update Draft Environmental Impact Report (DEIR), there was a study completed in 1999 referred to as the Potential Hazard from Tsunami and Seiche Waves Generated by Future Large Earthquakes within the Lake Tahoe Basin that modeled three earthquake scenarios within the Tahoe Basin and indicated that an earthquake with a magnitude of 7 would pose a potential hazard to shoreline development in both California and Nevada (Ichinose et al. 2000). These hazards would result from the development of seiche waves that could range from 3 to 10 meters (9.8 feet to 32.8 feet) high that could inundate shoreline development in the City within 16 minutes of the earthquake event (Ichinose et al. 2000). Shoreline development in the City’s Planning Area below 6,239 feet elevation could be subject to seiche inundation. This area includes the entire Tahoe Keys and Lakeside Park neighborhoods, and portions of the Tahoe Island, Tahoe Valley, and Tahoe Meadows neighborhoods. Other residential neighborhoods include portions of the Bijou/Al Tahoe and Stateline/Ski Run Community Plan areas. The City’s 2010 General Plan Update DEIR contains a map of the areas of potential seiche inundation (Figure

4.7-5 of the 2010 DEIR). Open space and recreation areas that are generally undeveloped would result in minimal impacts if a lake seiche event occurred. The City’s Local EOP and Emergency Management Plan includes response provisions for seiche waves hazards, such as a warning process when an earthquake event with a magnitude of 7 or greater occurs that would generate a seiche wave. This would ensure residents, employees, and visitors are warned and understand how to evacuate the area. 589
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-93 Figure 4-21 Stream Environment Zones (SEZ) within and around the City of South Lake Tahoe Extent (Magnitude/Severity)
Limited – Flood maps can be used as an indicator of flood extent. Flood depth and velocity also affect the extent of flood hazards and resulting damage. The deeper and faster flood flows become, the more 590
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-94 damage they can cause in a community. However, shallow flooding with high velocities (e.g., such as a flash flood event caused by precipitation) can cause as much damage as deep flooding with a slow velocity (e.g., from a riverine flood event). This typically happens when a channel migrates over a floodplain and redirects flows and transports debris and sediment.

While cities can implement measures to prevent or reduce the severity and magnitude of flood hazards, some level of risk often remains. These types of threats include upstream dam failure, infrastructure failure, and severe flood events that exceed flood design standards or drainage capacity, leading to flash flooding. Flood severity can be determined by logging peak discharge flows. This information is tracked by both FEMA and the USGS. FEMA’s BFE depth curve datasets provide further insight as to how much gets flooded of a community and where exactly, enhancing the level of detail on the magnitude of flooding that can affect a particular community. Based on the BFEs in the 2012 FIS, flood depths in the City range from 6,236 feet to 6,347 feet along Bijou Creek, 6,305 feet to 6,328 feet along Angora Creek tributary, 6,278 feet to 6,346 feet along Angora Creek, and 6,234 feet to 6,477 feet along the Upper Truckee River.

Other localized flooding from existing stormwater infrastructure, for example, is more difficult to estimate but could happen anywhere in the Planning Area and could be severe depending on the flood event itself and the conditions of the existing infrastructure. Table 4-28 below summarizes the general FEMAavailable flood zones for context.

Table 4-28 FEMA’s Special Flood Hazard Area (SFHA) Zone Descriptions Flood Zone Definition
FEMA Special Flood Hazard Areas (SFHA) Subject to Inundation by the 100- or 500-Year Floods Zone A 100-year floodplain, or areas with a 1% annual chance of flooding. Because detailed analyses are not performed these areas, no depths or base flood elevations are shown in Zone A areas.

Zone AE Detailed studies for the 100-year floodplain. The base floodplain where base flood elevations are provided.

AE Zones are now used on new format FIRMs instead of A1-A30 zones.

Zone AH Areas with a 1% chance of shallow flooding, usually in the form of a pong with an average depth ranging from 1 to 3 feet. These are flood elevations derived from detailed analyses.

Zone AO River or stream flood hazard areas and areas with a 1% or greater chance of shallow flooding each year, usually in the form of sheet flow, with an average depth ranging from 1 to 3 feet. Average flood depths derived from detailed analyses.

Zone A99 100-year floodplain, areas with a 1% annual chance of flooding that will be protected by a federal flood control system where construction has reached specified legal requirements. No depths or base flood elevations are shown within these zones.

Other Flood Areas
Floodway A regulatory floodway is the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height.

Zone X (shaded) Areas with a 0.2% annual chance flooding (1 in 500 chance), between the limits of the 100-year and 500- year floodplains. This zone is also used to designate base floodplains of lesser hazards, such as areas protected by levees from the 100-year flood, shallow flooding areas with average depths of less than one foot, or drainage areas less than one square mile.

Zone X
(unshaded)
500-year floodplain (0.2% annual chance). Area of minimal flood hazard.

Source: FEMA Flood Map Service Center, 2018
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-95 Previous Occurrences
The City of South Lake Tahoe has historically been
impacted by flooding from sources such as general
riverine and flash flooding from winter storms. Historical records are described below but may not represent all
historical events. The records below are from several
sources, including the National Center for Environmental Information (NCEI) database, which is managed by NOAA;
USGS; 2016 El Dorado County Operational Area HMP; the
2018 California SHMP, 2008 South Lake Tahoe Natural
HMP; the U.S. Department of Agriculture’s Secretarial
Disaster Designations; and, the OpenFEMA Disaster
Declaration dataset.

January 1 – 3, 1997 – Northern California and western
Nevada, including the Lake Tahoe Basin, were affected by floods during January 1-3, 1997. In the two California counties surrounding Lake Tahoe, El Dorado and Placer, about $91 million in estimated damage was attributed to floodwaters. The flooding in the Lake Tahoe Basin was mainly along the Upper Truckee River in the City of South Lake Tahoe.

In late December 1996, several winter storms produced a large snowpack (more than 180 percent of normal) in higher altitudes of the Sierra Nevada. Valleys along the eastern Sierra Nevada front were covered with a large snowpack as well. A subtropical storm system originating in the central Pacific Ocean then brought heavy rain to the Sierra Nevada from December 30, 1996, through January 3, 1997. During this period, the Natural Resource Conservation Service recorded 27.7 in. of precipitation at Squaw Valley, California (8,200 ft above sea level), and the National Weather Service recorded 11.6 inches at Tahoe City, California (6,230 ft). Rain falling below 10,000 ft depleted about 20 percent of the high-altitude snowpack between 7,000 and 10,000 feet and melted about 80 percent of the snowpack below 7,000 ft. This scenario was typical throughout the region and resulted in extensive flooding on the Truckee, Carson, Walker, and Susan Rivers, causing tremendous amounts of public and private damage throughout the eastern Sierra and extreme western Nevada.

There was so much rain and melted snow that Lake Tahoe was pushed over its legal limit by 3.5 inches, reaching an altitude of 6,229.39 feet on January 5th. This was the highest elevation of the lake since July 17, 1917. For El Dorado County, the Upper Truckee River reached its highest level ever on January 2nd.

The American River west of Echo Summit tore away several bridges that provided access to summer homes. U.S. Highway 50 received extensive damage from water undermining sections and also from mudslides. One injury was reported when a boulder dislodged by a saturated hillside slammed into a truck. A 43-year-old woman received serious head injuries. Estimated damage in El Dorado County was as follows: 1) public facilities: $17 million, 2) private owners and businesses: $5 million, and 3) Federal Highway System: $40.5 million.

December 31, 2005 - Localized flooding was reported in areas south of Lake Tahoe. Sierra Pacific Power Company reported that at least eight power poles were knocked down, most likely due to the saturated ground. Power lines were also downed when trees fell on them. Around 4,000 people were left without power south of Lake Tahoe. This was the record flood on Trout Creek in South Lake Tahoe and Tahoe Valley, flooding U.S. Highway 50. General Creek flooded California Highway 89 at Sugar Pine Point State Park. This flooding resulted in a total of around $1M in property damage.

July 18, 2002 - Heavy rain from thunderstorms caused street flooding in the City a little bit after noon.

There was hail later that day at around 4 pm as well.

Residents who lived on Colorado Court, South Lake
Tahoe, were evacuated on January 2, 1997, with the
help of a City of South Lake Tahoe dump truck
while others returned to their home to gather
belongings.

Photo credit: Tahoe Daily Tribune 2017
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-96 February 8 – 11, 2017 – Two significant waves of precipitation associated with an atmospheric river brought heavy rain and higher elevation (mainly above 6,500 feet) snowfall to northeast California.

Widespread rainfall totals between 5 and 8 inches were reported between the 6th and 10th, with rainfall and/or liquid-equivalent amounts up to between 10 and 16 inches near the northern Sierra crest. The rainfall brought widespread flooding to the region with several northeast California rivers coming out of their banks. Consequently, heavy rain combined with snow berms and clogged storm drains brought flooding to around 10 homes in South Lake Tahoe starting on the 8th. Bill and Shirley Avenues saw the most flooding damage per a KCRA news article. The flooding resulted in around $250K in property damage.

March 22 – 23, 2018 – Heavy rainfall caused flooding at two residences in South Lake Tahoe along Bill Avenue on March 22, 2018.

Probability of Future Occurrences
Likely – The 100-year flood is the flood that has a one percent chance in any given year of being equaled or exceeded, while the 500-year flood is expected to have a 0.2 percent chance of occurring (or being exceeded) in any year, respectively. As such, wet-mantle and rain-on-snow flooding will likely occur in the future, though localized stormwater flooding, general flash flooding and riverine flooding are also expected to take place especially during the wet months and heavy rain or storm events.

Climate Change Considerations
Emerging findings from California’s Fourth Climate Assessment show that costs associated with direct climate change impacts by 2050 will be dominated by human mortality, coastal damage, and the potential for droughts and mega-floods (California Natural Resources Agency 2018). Scientific studies outlined in the same assessment also indicated shifts in California’s precipitation regime, which show more dry days, more dry years, a longer dry season, mixed with increases in occasional heavy precipitation events and floods (i.e. a shift towards potentially less frequent but more extreme precipitation events). Studies also project great storm intensity with climate change, resulting in more direct runoff and flooding due to the flash flooding or precipitation nature of these expected events. As a result of fewer but more violent precipitation events, high-frequency flood events will increase with climate change. Also, with wildfires already being a problem in California, increasing periods of drought and lack of precipitation are expected to exacerbate conditions for fires to occur, and in turn, worsen the potential for runoff and flooding associated with burned areas due to increased impermeability and damage terrain and soils.

According to the City’s 2020 CAP, which is also based on California’s Fourth Climate Change Assessment Sierra Nevada report, annual temperatures and the intensity of precipitation events are projected to increase steadily over time in the Sierra Nevada region in the future (2020 CAP). These changes will result in increased heat waves, wildfire risk, and flooding, resulting in adverse effects on human health and safety, economic prosperity, infrastructure, and the provision of public services in the region and on the City. The northern Sierra Nevada experienced its wettest year on record in 2016 (California Natural Resources Agency 2018). As temperatures increase, the increase in precipitation falling as rain rather than snow also could lead to an increased potential for floods because water that would normally be held in the snowpack of the Sierra Nevada and Cascade Range until spring will flow into the Central Valley concurrently with winter rainstorm events. This Fourth Climate Assessment also indicates that climate change is expected to alter built water supply systems due to worsening storm conditions, so that current management practices for flood control and water supplies across the State of California may need to be revised. Moreover, the Plan states that as a result of these changes in temperature and precipitation patterns, local flooding hazards in the City are likely to increase over the coming century. The areas already subject to flood hazards will continue to experience flooding events, but these events will likely increase in frequency and severity, particularly in the winter months, as a larger percentage of areas within or near the City will experience annual precipitation falling as rain rather than snow due to warmer 593
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-97 temperatures. Considering the City’s reliance on tourism as a primary economic sector, long-term flooding impacts on transportation infrastructure in the City or along primary transportation routes leading to the City could result in secondary economic impacts from decreased visitation and tourism activity.

The City’s CAP listed adaptation strategies that target flooding, including implementing wetland and stream restoration projects, improving stormwater infrastructure to accommodate larger runoff events and mitigate flooding, preparing infrastructure to ensure capability for dealing with extreme heat conditions, runoff and flooding, and stabilizing vulnerable transportation infrastructure (e.g., access roads, bridges, trails) to prepare for flooding.

Based on El Dorado County’s 2017 Climate Change and Health Profile Report, gradually increasing temperatures, climate models predict an increase in the frequency and intensity of extreme weather events such as floods, and droughts. Meanwhile, increasing temperatures and changes in precipitation introduced by climate change may lead to intensified drought conditions, which may increase exposure to hazards including flash flooding. Refer to 4.3.3 Drought as well as 4.3.8 and 4.3.9 Severe Weather sections for details on related climate change predictions. For these reasons, climate change would have a “high” influence on flooding hazards.

Vulnerability Assessment
Flooding has occurred in the past within the 100-year floodplain and in other localized areas. In addition to the damage to area infrastructure and City facilities, other problems associated with flooding include erosion, sedimentation, degradation of water quality, loss of environmental resources, certain health hazards, and the inconvenience or potential financial and accessibility issues that come with road closures and other such effects.

For the following vulnerability assessment, GIS was used to identify and quantify the possible impacts of flooding within the City’s Planning Area. The following methodology was followed in creating these flood vulnerability maps and determining values at risk to the 100- and 500-year flood events.

Insurance Coverage and NFIP Claims and Losses for Repetitive Loss Properties The City of South Lake Tahoe joined the NFIP (regular entry) on July 3, 1978. The current effective map date is from April 3, 2012. NFIP Community Information System (CIS) insurance data indicates that as of September 14 24, 2021 there were 90 policies in place in the City, resulting in $ 28,424,100 of insurance in effect. Since the City began participating in the NFIP there have been 70 total closed losses, amounting to $ 868,236.72 in payments.

The NFIP defines a repetitive loss property as any insurable building for which two or more claims of more than $1,000 were paid by the NFIP within any rolling 10-year period since 1978. At least two of the claims must be more than 10 days apart but within 10 years of each other. A repetitive loss property may or may not be currently insured by the NFIP. The City of South Lake Tahoe’s latest CIS data, which was obtained on September 14, 2021, shows seven repetitive loss buildings (1 of which are insured) as defined by FEMA.

Repetitive loss properties have incurred 11 total losses, 2 of which were insured cases, and these accrued to $ 543,510.07 in payments from both building- and contents-related losses. Eight of these repetitive loss properties fell within B, C, and X flood hazard areas while three of these repetitive loss properties fell within AE, A, A1-A30, AO, AH flood hazard areas (FEMA 2019c). Table 4-29 below summarizes the repetitive loss information detailed in the City’s latest CIS report.

Table 4-29 City of South Lake Tahoe Repetitive Loss Payouts Repetitive Loss Component Zones AE, A, A1-30, AO, AH Zones B, C, X Total Total Buildings 2 5 7
Insured Buildings 1 0 1
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-98 Repetitive Loss Component Zones AE, A, A1-30, AO, AH Zones B, C, X Total Total Losses 3 8 11
Insured Losses 2 0 2
Total Payments $40,842.13 $502,667.94 $543,510.07
Building-Related Losses $40,842.13 $473,885.19 $514,727.32 Contents-Related Losses $0 $28,782.75 $28,782.75
Insured Payments $27,001.43 $0 $27,001.43
Building-Related Payments $27,001.43 $0 $27,001.43
Contents-Related Payments $0 $0 $0
Source: CIS Repetitive Loss report for the City of South Lake Tahoe (FEMA) 2021 Note: No repetitive loss information was noted for Zones VE, V, or V1-30; as such that column was excluded.

Property
This section summarizes the vulnerabilities to parcels and values at risk in the City. According to the information obtained via the GIS analysis, where the number and types of parcels falling in the 100- and 500-year floodplains were aggregated, the City has 370 parcels with total values equating to $143.6 million in both floodplains. A 25 percent damage factor was applied to the total value column of the tables below to estimate potential losses from flood-related hazards to the City’s parcels. Twenty-five percent is the typical loss ratio associated with a 2-foot-deep flood, based on FEMA and Army Corp of Engineer (Corps) depth-damage relationships. The total values were calculated by adding up the improved structure values of the parcels in the floodplains with the content values. These values were then estimated with the following formulas: a) residential and multi-family properties received contents valued at 50 percent of the parcel improved value; b) commercial and agricultural properties’ contents were valued at 100 percent of the parcel improved value; and, c) vacant parcels received 0 percent content values. These valuation assignments are founded on FEMA’s methodology for estimating contents within their loss estimation software, Hazus-MH.

Table 4-30 and Table 4-31 summarize the values at risk in the City’s 100- and 500-year floodplains.

Overall, South Lake Tahoe has 222 parcels valued at roughly $161.7 million in the 100-year floodplain, $40.4 million of which is estimated to be the potential loss if a flood of this nature were to take place. 148 parcels valued at roughly $63.4 million are found in the 500-year floodplain, $15.8 million of which is estimated to be the potential loss if an event of this magnitude were to take place. Combined, the potential losses estimated from both events would total $56.3 million.

Table 4-30 City of South Lake Tahoe Parcels in Floodplains by Parcel Type and Flood Event Flood
Event
Parcel Type Total
Parcels
Improved
Value
Contents
Value
Total Exposure
Value
Loss Estimate
(25% of the
Total Value)
Population
at Risk
100-year Commercial 9 $13,550,132 $13,550,132 $27,100,264 $6,775,066 NA Exempt 1 $0 $0 $0 $0 NA
Miscellaneous 2 $34,357 $34,357 $68,714 $17,179 NA
Residential 210 $89,680,538 $44,840,269 $134,520,807 $33,630,202 531 TOTAL 222 $103,265,027 $58,424,758 $161,689,785 $40,422,446 531 500-year Commercial 6 $5,574,375 $5,574,375 $11,148,750 $2,787,188 NA Exempt 1 $0 $0 $0 $0 NA
Residential 141 $34,803,488 $17,401,744 $52,205,232 $13,051,308 357 TOTAL 148 $40,377,863 $22,976,119 $63,353,982 $15,838,496 357 GRAND TOTAL 370 $143,642,890 $81,400,877 $225,043,767 $56,260,942 888 Sources: City of South Lake Tahoe GIS, El Dorado County Assessor’s Office, FEMA NFHL, Wood Parcel Analysis Figure 4-22 shows the locations of the parcels (properties) that fall in the 100- and 500-year (1% annual chance and 0.2% annual chance) floodplains.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-100 People
Of greatest concern in the event of a flooding event is the potential for injury or loss of life. City 2018 U.S.

Census Bureau estimates were obtained, which indicate the average number of persons per household for the City. The City’s average household size is 2.53, and this metric was multiplied by the number of parcels of residential nature at risk of flooding to determine the total potential affected population. The population at risk estimates are summarized in the last column of Table 4-30 and Figure 4-22 in the pages above, by flood event type and parcel type. The results were totaled for all the flood hazard zones. As the previous table indicates, there are around 888 people at risk of flooding caused by any of the flood events overlapping with residential properties, where 531 people are found in the 100-year floodplain and 357 people in the 500-year floodplain. Given the number of households and populations identified as socially vulnerable, disadvantaged, or sensitive in the City’s Planning Area and the proximity of these census tracts and block groups to the flood zones, it is assumed that a portion of this population segment may also be disproportionately impacted during a flood event.

Economy
Similar to a dam inundation event which would affect infrastructure (e.g. roads), homes, and populations (possibly displacing families), impacts to the local economy could include business interruptions, lost or reduced wages from a potential relocation of populations, infrastructure and resource downtime costs, and reduced City revenues from lack of tourism or inability to run/maintain certain services (like potable water based utilities). Other secondary hazard impacts such as reduced water quality or resource availability, which could, in turn, raise costs of water processing and distribution are also possible results from a severe flooding event, whether from riverine flooding, flash flooding, or an event caused by local stormwater/drainage infrastructure failures.

Critical Facilities and Infrastructure
According to the City’s 2008 HMP, the majority of flood-related hazards in the City are transportationrelated floods. Waters do not normally cause road closure due to inundation. Rather, roads are closed due to varying degrees of erosion-related washouts. At the most minimal levels, road shoulders are compromised due to high levels of runoff from precipitation. Roads may be reduced to passage in only one direction at a time. At the most severe levels, whole road structures are eroded from high river discharges for distances over one hundred yards. In these instances, bridge facilities can be threatened or lost because of debris impacting the bridge structures. In either case, road damage and road closure affect the transportation infrastructure of the City, interrupting the movement of people, supplies, and services while reducing productivity because of increased commute time. The City's public safety response is affected as well, slowing the arrival of police officers and fire suppression personnel as well as other emergency response personnel.

Flood-related erosion can cause damage to homes, businesses, and government structures, including damage to ancillary structures, utilities, and parking facilities. Structural foundation undercutting is the most prevalent form of damage to structures. Structures can also be damaged from trees falling as a result of water-logged soils. Electrical power outages happen and the interruption of power causes many problems. Lost power is usually a precursor to the closure of government offices, or the offices may be subject to reduced schedules. Public schools may also be closed or on a delayed start schedule.

Critical facilities are those community components that are most needed to withstand the impacts of disasters as previously described. GIS was used to determine what critical facilities and infrastructure occur within South Lake Tahoe’s mapped flood hazard areas. The NFHL flood layers previously discussed were used to identify where the 1% annual chance and 0.2% annual chance floodplains intersected with critical facilities. Figure 4-2 illustrates the locations of these critical facilities relative to the floodplains. Table 4-31 597
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-101 provides an inventory of the 15 facilities that occur within the floodplains. The impact to the community could be substantial if these critical facilities were damaged or destroyed during a flood event, particularly those which provide lifeline utilities or health/medical services. Overall, there are a total of six Food, Water, Shelter facilities together with nine Transportation Facilities found in the floodplains, including the Lake Tahoe Airport that would be at risk if a flooding event were to happen.

Table 4-31 Critical Facilities in the 1% and 0.2% Annual Chance Floodplains in the City Flood Event
FEMA Lifeline
1%
Annual
Chance

0.2%
Annual
Chance
Total
Communications 0 0 0
Energy 0 0 0
Food, Water, Shelter 4 2 6
Hazardous Material 0 0 0
Health and Medical 0 0 0
Safety and Security 0 0 0
Transportation 7 2 9
Total 11 4 15
Source: The City of South Lake Tahoe GIS, HIFLD, FEMA NFHL, Wood GIS Analysis Historic, Cultural, and Natural Resources
Among the City’s historical and cultural resources mentioned in 4.2 Asset Summary, only Tahoe Meadows is located within the City Limit while the others are located within the City’s SOI or the general vicinity. As mentioned previously, climate change studies at the county and regional level indicate the likelihood that increasingly unpredictable flash flooding and uncertainty in storm occurrence will lead to a worsening in erosion and sedimentation conditions. However, natural areas within the floodplain often benefit from periodic flooding as a naturally recurring phenomenon, and these natural areas often reduce flood impacts by allowing absorption and infiltration of floodwaters. Nevertheless, other cultural or historical resources such as older buildings or districts may be more affected by these flooding hazards, given their likely older construction methods, weaker materials, and potential failure to meet current building code standards.

Future Development
According to the Health and Safety Element of the City’s 2011 General Plan, the City shall locate all new development outside of TRPA-defined SEZs and FEMA-defined 100-year floodplains. The City’s Floodplain Management Ordinance provides similar direction for new and existing developments located within SFHAs to reduce future flood damage through the implementation of building techniques that minimize the potential loss of life and property due to development in floodplains. Also, as previously noted, where the City’s Floodplain Management Ordinance, TRPA Code of Ordinances, and Basin Plan conflict or overlap, the more stringent restrictions prevail. he City shall also provide incentives to remove private development from SEZs and 100-year flood plains to reduce drainage problems and damage to public and private property. The City will support the restoration of identified floodplains through the relocation of existing tourist accommodations (e.g., hotels, motels) within floodplains and the removal of floodplain improvements. In addition, the City will promote the aesthetic, environmental, and functional improvement of natural drainage ways where watercourses have been disrupted in such a manner as to protect abutting uses from flooding while taking into consideration environmental, recreational, and open space needs. The City will also continue with its flood prevention measures, including the Cooperating Technical Partnership with FEMA, participation in NFIP, as well as the implementation of the FIRM and floodplain management to minimize the loss of life, injury, and property damage due to flooding. 598
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-102 The City implements several of these General Plan policies through their Floodplain Management Ordinance that was adopted in 2001, which provides direction for new and existing developments located within SFHAs. Chapter 6.65 of the City Municipal Code contains six articles that cover a variety of topics, including methods of reducing flood losses and standards and provisions for flood hazard reduction. The primary goal of this ordinance is to reduce future flood damage through the implementation of building techniques that minimize the potential loss of life and property due to development in floodplains. It also consistent with the more restrictive floodplain development standards found in the TRPA Regional Plan and the Lahontan RWQCB’s Basin Plan. In summary, the regional and City’s Floodplain Ordinance both ensure flood standards are in place for new development in order to minimize flood hazards.

Risk Summary
• Overall the significance of flood hazards is High.
• Floods impacts will vary by location and severity and will likely only affect certain areas of the City at any one time.
• Based on the risk assessment, floods will continue to have economic impacts on certain areas of the City, and the estimated loss for properties amounts to $56.3 million (with a total of 888 potential people at risk), in addition to the 15 critical facilities which fall in the floodplains. • 222 properties valued at roughly $161.7 million are located in the 100-year floodplains. 148 properties were found at risk of the 500-year (0.2 percent annual chance) floodplain, roughly valued at $63.4 million.
• Five noteworthy flooding events have taken place in South Lake Tahoe since 1982. These caused significant damages and several required evacuations, though other minor flooding cases have taken place. The worst two events to record for the City are the New Year’s flood of January 1997, which caused estimated damage in El Dorado County including 1) public facilities: $17 million, 2) private owners and businesses: $5 million, and 3) Federal Highway System: $40.5 million and the end-of-year December 2005 flood, which caused $1 million in property damage. • Impacts that are not directly quantified but could be anticipated in large future events include: 1) injury and loss of life; 2) disruption of and damage to public infrastructure; 3) disruption to trade, commerce, commuting, mobility, and other activities that may rely on the road networks; 4) health hazards associated with mold and mildew; 5) significant direct and indirect economic impact (jobs, sales, tax revenue) upon the community; and 6) negative impact on commercial and residential property values.
• NFIP CIS insurance data indicates there were 88 policies in place in the City, resulting in $27,875,900 of insurance in effect. Since the City began participating in the NFIP there have been 70 total closed losses, amounting to $868,236.72 in payments. There are seven repetitive loss buildings (1 of which are insured) in South Lake Tahoe. Repetitive loss properties have incurred 11 total losses, 2 of which were insured cases, and these accrued to $ 543,510.07 in payments from both building- and contentsrelated losses.

4.3.6 Landslide and Debris Flows
Hazard Problem/Description
Landslide is a generic term that is defined as the downward sliding of a relatively dry mass of earth and rock. An even more simplistic definition is "slope failure," which includes landsides, mudflows, debris flows, and rockfall that may cause damage. The primary factor involved in landslides is gravity, but three other factors have varying degrees of influence. They are:
• Slope angle
• Slope material, and
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Gravity is the constant in any equation trying to quantify the stability or instability of a slope face. Slope angle, slope material, and the amount of water are the variable factors that, combined with gravity, determine slope stability. Other factors that identify the stability of a slope to a lesser degree are vegetation and climate.

Landslides are categorized into groups using two variables; the type of movement and the type of material that is involved. Type of movement is categorized into three groups:
• Falls
• Slides, and
• Flows
The amount of water usually is the defining component when classifying the movement. In “falls”, very little water is present, whereas in “flows”, there is a substantial amount of water involved. The type of material involved is broken into three groups: soil (earth), rock, and debris. These groups help identify rockfalls, earthflows, or debris slides and each of these events is determined by the composition of materials and the speed of movement. A rockfall is dry and fast while a debris flow is wet and fast.

Regardless of the speed of the slide, the materials within the slide, or the amount of water present in the movement, landslides are a serious natural hazard. While they rarely result in the loss of human life they are attributed to between 25 and 50 deaths annually, and they commonly result in disruptions in public services, including emergency response; blocked transportation routes, diverted water flow in creeks and streams and drainage ways, and contamination of water supplies, which can cause up to two billion dollars in damage annually in the United States.

Landslides are a natural process and are unavoidable in the long term, being due to the patient nature of gravity and the gradual weathering of the earth's surface. Although natural disturbances like earthquakes and storms can trigger landslide events, humans can also have a direct effect on and even accelerate landslide occurrence. Any time a slope is graded or cut into, a formerly stable slope can become unstable, eventually seeking a new equilibrium in the form of a landslide. (South Lake Tahoe 2008). Landslides are usually the result of snow or rain-saturated soils and large landslides can often be the combination of more than one landslide type (Cal OES 2018).

Mud and Debris Flow
Mudslide is a mass of water and fine-grained earth that flows down a stream, ravine, canyon, arroyo, or gulch. If more than half of the solids in the mass are larger than sand grains (rocks, stones, boulders), the event is called a debris flow. There are two types of debris flows: those related to shallow landslides and post-wildfire debris flows. A debris flow associated with a shallow landslide may occur due to soil failure where soil liquefies and runs downhill and has a discrete initiation zone and depositional area much like an avalanche. These tend to occur following periods of heavy rainfall when soil is saturated. A debris fan is a similar conical landform produced by successive mud and debris flow deposits, and the likely spot for a future event. Mud and debris flow problems can be exacerbated by wildfires that remove vegetation that serves to stabilize soil from erosion which in turn increases runoff and channelization and picks up debris as it moves downslope. Heavy rains on the denuded landscape can lead to rapid development of destructive mudflows. The most recent post-fire debris flow event in California occurred in Santa Barbara County in January 2018 following the Thomas Fire when debris flowed from several canyons and deposited the material onto an urbanized alluvial fan in Montecito and Carpinteria (Cal OES 2018). 600
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-104 Rockfall
A rockfall is the falling of a detached mass of rock from a cliff or down a very steep slope. Weathering and decomposition of geological materials produce conditions favorable to rockfalls. Rockfalls are caused by the loss of support or weakened soil layers through erosion or triggered by ice wedging, root growth, or ground shaking. Changes to an area or slope such as cutting, and filling activities can also increase the risk of a rockfall. Rocks in a rockfall can be of any dimension, from the size of baseballs to houses. Rockfalls can threaten human life, impact transportation corridors and communication systems and result in other property damage. Rockfalls and landslides are influenced by seasonal patterns, precipitation, and temperature patterns. Earthquakes could trigger rockfalls and landslides too.

Soil Hazards: Erosion and Deposition, Expansive Soil and Subsidence Erosion is “the removal and simultaneous transportation of earth materials from one location to another by water, wind, waves, or moving ice.” Erosion is the opposite of deposition, which is defined as the placing or laying down of eroded earthen materials or sediment in a new location or landform.. Both erosion and deposition are continually occurring phenomena, although the rate of erosion and deposition varies tremendously and can be affected by a variety of factors including the rate of scouring, the type of material being eroded, and the presence or absence of vegetation.

Expansive and collapsible soils are some of the most widely distributed and costly geologic hazards. They are also known as metastable soils and are unsaturated soils that undergo changes in volume and settlement in response to wetting and drying, often resulting in severe damage to structures. The sudden and usually large volume change could cause considerable structural damage. Expansive soil and rock are characterized by clayey material that shrinks as it dries or swells as it becomes wet.

Land subsidence is defined as the vertical sinking of the land over natural or manmade underground voids. Subsidence is common in several areas of California, usually as a result of groundwater pumping, peat loss, or oil and gas extraction. Fluctuations in the level of underground water caused by pumping or by injecting fluids into the earth can initiate sinking to fill the space previously occupied by water or soluble minerals. Weight, including surface developments such as roads, reservoirs, and buildings, and manmade vibrations from such activities as blasting and heavy truck or train traffic can accelerate the natural processes of subsidence, or induce subsidence over manmade voids.

The 2012 TRPA Regional Plan listed soils as a subelement under the Plan’s Conservation Element. In addition to serving as a growth medium for plants, soil provides numerous chemical, physical, and biological functions that are critical to sustaining healthy ecosystems and maintaining environmental quality, including water quality. One example of goals set up for soils is minimizing soil erosion and the loss of soil productivity. A relevant policy example is to maintain seasonal limitations on grounddisturbing activities during the wet season (October 15 to May 1) and identify limited exceptions for activities that are necessary to preserve public health and safety or for erosion control. Soil is also mentioned in the Vegetation subelement and Stream Environmental Zone subelement because certain policies and goals established in these two subelements also relate to restoring and preserving soil health. (TRPA 2012 Regional Plan)
Location
Limited – The City of South Lake Tahoe's terrain and climate combine to create conditions conducive to landslides. The threat of landslides is generally distributed throughout the year. Most landslide events are associated with and resultant from other natural hazards such as seismic activity or floods and the best predictor of where landslides may occur is the location of past events. As shown in Figure 4-23, there are a few areas within the City that possess a moderate to medium susceptibility to landslides. Areas towards the east part of the City exhibit medium to relatively high susceptibility to landslides; these areas include 601
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-105 the terrain behind Van Sickle Bi-State Park and the base of Heavenly Mountain Resort. Nearly all the areas along the SOI boundary exhibit at least moderate and sometimes high susceptibility to landslides.

Furthermore, almost the entire region surrounding the City show moderate to high susceptibility to landslides, but much of those areas are in remote and undeveloped locations, which reduces the potential impact on people, property and infrastructure, but could still potentially impact the transportation in to and out from the City as well as the availability of public safety services. 602
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-106 Figure 4-23 South Lake Tahoe Deep-Seated Landslide Susceptibility 603
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-107 Extent (Magnitude/Severity)
Limited – The extent of landslides and debris flow events within the City can range from negligible to significant. Landslides that occur within the City are most often experienced as part of a larger, more widespread natural hazard event. Landslides can take place because of severe storms, floods, and earthquakes. They can also happen as an aftermath of wildland fires. When landslides are ancillary events within larger natural hazard events, the dangers resulting from these larger hazard events combined with landslides would lead to much worse damage on properties, people and infrastructure.

Landslides and rockslides can result in the destruction of infrastructure such as water and sewer lines, electrical and telecommunications utilities and drainage where they are present. If power lines are compromised within the slide, electrical power can be lost. Moreover, the length of time during which power is interrupted is a direct result of the slide’s size and its impact upon the power lines and electrical infrastructure. In addition, water lines and other buried facilities can be put in danger or lost to a landslide.

Roads and highways are also often victimized by landslide events. When roads are compromised by landslides, motorist safety is threatened, and travel time is lengthened. Emergency personnel response time is also affected.

A GIS analysis of exposure to landslide hazard indicates that 1,888 parcels (16% of the City’s total parcels) are potentially within landslides hazard areas. $6,088 million of property value and 4,703 people’s lives would be at risk if a deep-seated landslide were to happen.

Previous Occurrences
Although no lives have been lost because of landslides, the threat to life and property can occur. In recent history, landslides occurred as a result of the weather associated with the January 1997 storm; however, there have not been any disaster declarations associated with landslides in the City of South Lake Tahoe.

According to records from the California Department of Conservation’s Geological Survey, there have been two recent records of landslides that happened within the SOI of South Lake Tahoe. Both landslide events happened along Highway 50 and were to the south of the City.

April 9, 2021 – Rockfall covered Highway 50 near Echo Summit with large boulders. One vehicle collided with boulders and overturned.

December 2, 2019 – 2 miles south of Echo Summit boulders covered westbound lane of US-50.

Figure 4-24 below shows the location of these two landslide events. 604
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-108 Figure 4-24 Recent landslide events near South Lake Tahoe Source: Geologic Mapping Program, California Geological Survey, CA Department of Conservation Probability of Future Occurrences
Highly likely – The City’s high-relief mountainous terrain makes the City susceptible to landslide events.

The degree of slope directly affects the gravitational force exerted upon the land and its potential to slide.

As long as gravity remains the controlling factor upon the landscape, landslides are naturally occurring events that will inevitably happen. Moreover, when other natural hazards that trigger landslides occur, the probability of a landslide event happening increases, so does the potential threat. For example, the 12/2/2019
4/9/2021
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Climate Change Considerations
Landslides and debris flows can result from intense rainfall and runoff events. Projected climate change variances in rainfall events may result in more high-intensity events, including flash flooding and drymantle flooding, which may increase landslide frequency. In addition, the increased potential of wildfire occurrence escalates the risk of landslide and debris flows in the period following a wildfire when slopes lack vegetation to stabilize soils and burned soil surfaces create more rainfall runoff. As climate change affects the length of the wildfire season, a higher frequency of large fires may occur into late fall, when conditions remain dry, and then be followed immediately by intense rains early in the winter, as occurred with the Thomas Fire in December 2017 and subsequent Montecito and Carpinteria debris flow in January 2018 in Santa Barbara County (CA SHMP 2018).

Vulnerability Assessment
General Property
Landslides directly damage engineered structures in two general ways: 1) disruption of structural foundations caused by differential movement and deformation of the ground upon which the structure sits, and 2) physical impact of debris moving downslope against structures located in the travel path.

As previously mentioned in 4.2.1 Total Assets at Risk, there are approximately 11,757 parcels containing $6,088 million of property improvements in the City of South Lake Tahoe, which considers improved values of properties. Based on the GIS analysis, there is a total of 1,888 parcels (16% of the 11,757 total parcels) potentially within landslide hazard areas. The majority of this exposure is in the western unincorporated portion of the County outside the Planning Area. There is a high level of uncertainty as to the actual risk to these exposed parcels, thus a more specific loss estimation is not provided.

Table 4-32 summarizes the specific landslide exposure result by property/parcel type. Only parcels with improvement values greater than zero were used in the analysis, and this method assumes that improved parcels have a structure of some type.

A more detailed, site-specific analysis would be needed to assess actual risk within the identified parcels.

Table 4-32 South Lake Tahoe Improved Properties at Risk to Deep-Seated Landslide Susceptibility
Property Type Improved
Parcel Count
Improved
Value
Estimated
Content Value
Total Exposure
Value
Population
Commercial 24 $13,747,510 $13,747,510 $27,495,020 -
Exempt 1 $0 $0 $0 -
Industrial 4 $1,857,657 $2,786,486 $4,644,143 -
Residential 1,859 $612,702,597 $306,351,299 $919,053,896 4,703 Total 1,888 $628,307,764 $322,885,294 $951,193,058 4,703 Source: Dept. of Conservation, California Geological Survey, South Lake Tahoe City Assessor, Wood GIS Analysis Figure 4-25 below breaks down the numbers of exposed buildings by landslide class, as shown previously in Figure 4-24;
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-110 Figure 4-25 Total Parcel Counts by Landslide Class
*Total Counts of parcels that are susceptible to deep-seated landslide hazards. As mentioned above and shown in the graph., there are 1,888 exposed parcels.

Data source: Wood GIS Analysis
People
People could be susceptible if they are caught in a landslide or debris flow, potentially leading to injury or death. There is also a danger to drivers operating vehicles, as rocks and debris can strike vehicles passing through the hazard area or cause dangerous shifts in roadways. An estimated 4,703 people are exposed to potential slope failure or landslides based on the parcel analysis. It is not likely that landslides will occur without warning and direct impacts to people are suspected to be minimal, however, some debris flow and rockfall events can occur with very short or no warning time. Therefore, information on where these events have already occurred or where conditions may support such events would help with preparedness when certain precursor events like prolonged rainfall may trigger soil instability.

Critical Facilities and Infrastructure
In addition to buildings, utilities and transportation structures are vulnerable to the impact and ground deformation caused by slope failures. They present a particular vulnerability because of their geographic extent and susceptibility to physical distress. Lifelines are generally linear structures such as roads, bridges and electrical power transmission infrastructure that, because of their geographic extent, have a greater chance of being affected by ground failure due to greater hazard exposure.

Extension, bending, and compression caused by ground deformation can break lifelines. Failure of any component along the lifeline can fail to deliver service over a large region. Once broken, the transmission of the commodity through the lifeline ceases, which can have catastrophic repercussions down the line:
loss of power to critical facilities such as hospitals, impaired disposal of sewage, contamination of water supplies, disruption of all forms of transportation, release of flammable fuels, and so on. Therefore, the overall impact of lifeline failures, including secondary failure of systems that depend on lifelines, can be much greater than the impact of individual building failures. Table 4-33 summarizes the critical facilities' exposure to landslide hazards.
0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000
Class 3
Class 6
Class 7
Class 9
Class 10
Total Count*
Parcel Counts
Landslide Class
Total Parcel Counts by Landslide Class
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-111 Table 4-33 Critical Facilities Exposed to Landslide Hazard by FEMA Lifeline & Landslide Class FEMA Lifeline Landslide Class
Class 6 Class 7 Class 8 Class 9 Class 10 Total Count
Communications 3 0 1 0 0 4
Energy 0 1 0 0 0 1
Food, Water, Shelter 3 22 0 3 4 32
Hazardous Material 0 0 0 0 0 0
Health and Medical 0 1 0 0 0 1
Safety and Security 0 4 0 2 0 6
Transportation 0 2 0 0 0 2
Total 6 30 1 5 4 46
Source: California Geological Survey, HIFLD, Wood GIS Analysis Out of the total 195 critical facilities and infrastructure, 46 are exposed to landslide hazards. Facilities that belong to the Food, Water, Shelter lifeline make up most of the exposed facilities (32 out of 46). Most of these Food, Water, Shelter lifeline facilities are exposed to Class 7 landslides.

Economy
Economic impacts typically center around transportation routes temporarily closed by debris flow or landslide activity. These roads may be used to transport goods across the County or provide access for commuters, visitors, and tourists. Depending on the amount of damage, the road may simply need to be cleaned off or may require some level of reconstruction.

Historic, Cultural, and Natural Resources
As primarily a natural process, landslides and debris flows can have varying impacts on the natural environment; debris flows have the potential to permanently alter the natural landscape.

Future Development
The severity of landslide problems is directly related to the extent of human activity in hazard areas.

Human activities such as property development and road construction can also exacerbate the occurrence of landslides. Future development should take place carefully to prevent landslide damage to property or people. Adverse effects can be mitigated by early recognition and avoiding incompatible land uses in these areas or by corrective engineering. Improving mapping and information on landslide hazards and incorporating this information into the development review process could prevent siting of structures and infrastructure in identified landslide hazard areas. Additional preventive measures include prohibiting habitable structures atop unconsolidated landslide debris, discouraging grading and construction on slopes greater than a certain degree such as 30%, and enforcing grading standards of the International Building Code.

The City’s 2020 CAP listed “Stabilize vulnerable transportation infrastructure (e.g., access roads, bridges, trails) to prepare for flooding or landslide events” as one of the transportation-related strategies to lower and mitigate the risk of landslides, flooding and wildfire near access roads.

Risk Summary
• The City’s terrain and climate combine to create conditions conducive to landslides, debris flows, and rockfalls; the threat of landslides is generally distributed throughout the year; most landslide events are associated with and the result of other natural hazards. 608
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-112 • Much of the high-relief topography in and around the City can be identified as land susceptible to landslides. Much of that land though is in remote and undeveloped locations, which reduces the potential damage on people, property, and infrastructure. • People are most commonly at risk if they are caught in a landslide or debris flow, including when driving through a hazard area; 4,703 people would be at risk if a deep-seated landslide were to happen in the City.
• Property loss is rare, but 16% of the total improved parcels analyzed would be exposed to landslides, leading to a $951.2 million loss if a deep-seated landslide were to happen. • Landslides can disrupt major transportation corridors, possibly affecting the local tourist economy and shipment of goods.
• 46 critical facilities and infrastructure such as water and sewer lines, electrical and telecommunications utilities and drainage could be damaged by slope failure. Disrupted transportation routes occur occasionally, usually during or following heavy rainstorms, and cause considerable inconvenience. • The overall significance of landslides in the City of South Lake Tahoe is Medium.

4.3.7 Severe Weather: General
Severe weather is generally any destructive weather event. For this plan, severe weather is broken down as follows:
• Winter Storms/Heavy Snow
• Thunderstorms/Heavy Rain/Hail/Lightning/High Winds
The NOAA NCEI has been tracking severe weather since 1950. Their Storm Events Database tracks severe weather events on a county basis and contains data on the following: all weather events from 1993 to current (except from 6/1993-7/1993); and additional data from the Storm Prediction Center, which includes tornadoes (1950-1992), thunderstorm winds (1955-1992), and hail (1955-1992). This database contains 811 severe weather events that occurred in El Dorado County between January 1, 1950, and August 3, 2021. Table 4-34 summarizes these events.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-113 Table 4-34 NCEI Hazard Event Reports for the El Dorado County* 1950-2021 Type # of Events Property Loss ($) Crop Loss ($) Deaths Injuries Avalanche 18 0 0 9 12
Debris Flow 13 6,542,000 0 0 0
Dense Fog 13 2,320,000 0 6 38
Dense Smoke 3 0 0 0 0
Extreme Cold/Wind Chill 1 0 0 0 0
Flash Flood 2 15,000,000 0 0 0
Flood 42 10,540,000 7,800,000 2 1
Frost/Freeze 8 200,000 5,000,000 0 0
Funnel Cloud 1 0 0 0 0
Hail 20 1,000 586,000 0 5
Heat 30 0 0 0 18
Heavy Rain 148 100,000 10,250,000 0 0
Heavy Snow** 500+ 1,675,000 0 1 4
High Wind 173 13,579,500 48,000 1 3
Lightning 0 0 0 0 0
Strong Winds 54 5,863,000 0 3 2
Tornado 5 1,002,500 0 0 0
Winter Storm 247 665,000 0 3 5
Total*** 778 53,908,500 236,840,000 25 88
Source: NOAA’s National Centers for Environmental Information https://www.ncdc.noaa.gov/stormevents/ *Note any reference to a coastal type weather event for El Dorado County has been excluded from this table. **Number of events for heavy snow exceeds 500. The data shown here is for the date range between January 1, 2001, and August 3, 2021 ***Wind Losses reflect totals for all impacted areas, inclusive of El Dorado County The NCEI table above summarizes severe weather events that have occurred in El Dorado County. Only a few of the events resulted in state and federal disaster declarations. While the HMPC recognizes these inconsistencies, this data provides value in depicting the County’s “big picture” hazard environment as it relates to severe weather events.

4.3.8 Severe Weather: Winter Storms/Heavy Snow
Hazard Description
Winter snowstorms are often large areas of low pressure originating from the Gulf of Alaska and then moving into the western United States. As the moist air masses push across the Sierra Nevada and other Great Basin mountains, the air masses cool and the water condenses as snow. Wind in combination with the snow can cause reduced visibilities and deep snowdrifts. In addition, heavy snow can cause avalanches in areas along steep terrain. In some instances, freezing rain occurs, when very cold inland arctic air becomes trapped under warm moist air. The National Weather Service (NWS) in Reno issues winter storm watches/warnings/advisories for heavy snow and provides briefings to Emergency Managers when winter storms are forecast.

The same winter storms also produce periods of widespread high winds in the Sierra Nevada and Great Basin. These winds of 40-60 mph typically precede the snow portion of a winter storm by a day or so – and are the most common from late fall through spring. Winter storms can include heavy snow, ice, and blizzard conditions. Some winter storms are accompanied by strong winds, creating blizzard conditions with blinding wind-driven snow, severe drifting, and dangerous wind chills. Strong winds with these intense storms and cold fronts can knock down trees, utility poles, and power lines. Blowing snow can 610
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-114 reduce visibility to only a few feet in areas where there are no trees or buildings. Serious vehicle accidents can also result in injuries and deaths.

Heavy snow can immobilize a region, stranding commuters, stopping the flow of supplies, and disrupting emergency and medical services. Accumulations of snow can collapse roofs and knock down trees and power lines. In rural areas, homes and farms may be isolated for days, and unprotected livestock may be lost. The cost of snow removal, damage repair, and business losses can have a tremendous impact on the City. Moreover, heavy accumulations of ice can bring down trees, electrical wires, telephone poles and lines, and communication towers. Communications and power can be disrupted for days until the damage can be repaired. Even small accumulations of ice may cause extreme hazards to motorists and pedestrians.

Location
Extensive – The City of South Lake Tahoe is located along the crest of the Sierra Nevada mountain range at an elevation of 6,300 feet above mean sea level (msl), where the mountains act as a lifting mechanism as air masses migrate over them, increasing the chance for precipitation. The City’s proximity to the Pacific Ocean, together with the City’s winter storm track, bring cold and moist marine polar air masses over the City throughout much of the year, especially during winter months. These four climatic factors – high altitude, mountain barriers, prevailing winter storm tracks, and air masses create a higher than average potential for severe winter storms within the region and within the City of South Lake Tahoe.

For the City of South Lake Tahoe, January through June and September through December are months with snowfall. The City receives around 114 inches of snow annually. The month with the most snowfall is March when around 27 inches of snow precipitates. (https://www.weather-us.com/en/californiausa/south-lake-tahoe-climate; NOAA NWS; World Climate.) The four climatic factors mentioned above that contribute to winter storms in the City also apply to its heavy snow events.

Extent (Magnitude/Severity)
Critical – The heavy snow and winter storms that occur in the City and all of California are often the result of an atmospheric river (AR). ARs are categorized by a unit of measurement known as the Integrated Water Vapor Transport (IVT), which considers the amount of water vapor in the system and the wind that moves it around. For a storm to be classified as an AR it has to reach an IVT threshold of 250 units; 1,000 IVT or more is considered to be “extreme” (Arcuni, 2019). In 2019, a system for categorizing the strength and impacts of atmospheric rivers was developed by the Center for Western Weather and Water Extremes (CW3E), out of the Scripps Institution of Oceanography at the University of California San Diego. The newly developed scale ranks ARs into five categories from weak to exceptional. Unlike the Fujita scale for tornadoes that focuses on potential damages, the AR scale accounts for both storms that may be hazardous and storms that can provide benefits to the local water supply. A category one AR is considered to be primarily beneficial, generally lasting only 24 hours and produces modest rainfall. On the other end of the scale, a category five AR is considered “exceptional” and primarily hazardous, lasting for several days and associated with heavy rainfall and runoff that may cause significant damages. Table 4-35 describes the scale further. The center developed the scale as a tool for officials with an operational need to assess flooding potential in their jurisdictions before the storms make landfall.

In both February 2018 and 2019 the West Coast experienced six atmospheric rivers. But as Figure 4-26 from the Center for Western Weather and Water Extremes shows, California experienced vastly different precipitation totals due to the location of where the atmospheric river made landfall as well as each AR’s IVT. Using the AR scale developed by CW3E, the ARs in February 2019 were all considered to be moderate to extreme and concentrated more on California, resulting in heavy precipitation, whereas in February 2018, no major ARs impacted California.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-115 Table 4-35 Atmospheric River (AR) Categories
Category Potential Impacts
AR Cat 1: Weak Primarily beneficial. For example, a Feb. 2, 2017 AR hit California, lasted 24 hours at the coast, and produced modest rainfall.

AR Cat 2: Moderate Mostly beneficial, but also somewhat hazardous. An atmospheric river on Nov. 19-20, 2016 hit Northern California, lasted 42 hours at the coast, and produced several inches of rain that helped replenish low reservoirs after a drought.

AR Cat 3: Strong Balance of beneficial and hazardous. An atmospheric river on Oct. 14-15, 2016 lasted 36 hours at the coast, produced 5-10 inches of rain that helped refill reservoirs after a drought, but also caused some rivers to rise to just below flood stage.

AR Cat 4: Extreme Mostly hazardous, but also beneficial. For example, an atmospheric river on Jan. 8-9, 2017 that persisted for 36 hours produced up to 14 inches of rain in the Sierra Nevada and caused at least a dozen rivers to reach flood stage.

AR Cat 5: Exceptional Primarily hazardous. For example, a Dec. 29, 1996 to Jan. 2, 1997 atmospheric river lasted over 100 hours at the Central California coast. The associated heavy precipitation and runoff caused more than $1 billion in damages.

Source: Center for Western Weather and Water Extremes, Scripps Institution of Oceanography at UC San Diego. Scale was developed by F. Martin Ralph Director of CW3E in collaboration with Jonathan Rutz of NWS 612
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-116 Figure 4-26 Atmospheric River (AR) Strength and Land Distribution, February 2018 vs. February 2019 Source: Center for Western Weather and Water Extremes, Scripps Institution of Oceanography at UC San Diego 613
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-117 The City of South Lake Tahoe receives most of its annual rainfall from November to May, which overlaps with the time during which the City receives most of its snowfall. Figure 4-27 shows the average monthly rainfall at South Lake Tahoe.

Figure 4-27 Average Monthly Rainfall in South Lake Tahoe Sources: https://www.weather-us.com/en/california-usa/south-lake-tahoe-climate; NOAA NWS; World Climate Winter weather results in property damage, localized power and phone outages, and closures of streets, highways, schools, businesses, and nonessential government operations. People can also become isolated from essential services in their homes and vehicles. A winter storm can escalate, creating life-threatening situations when emergency response is limited by severe winter conditions.

An example of a severe winter storm event in the City of South Lake Tahoe is the winter storm of December 2010. In two days, 12 to 18 inches of heavy, wet snow fell in the area of the City, causing trees and tree limbs to fall on power lines, which contributed to power outages for more than 10,000 power customers (Tahoe Daily Tribune 2010). (“Winter Storm Knocks out Power and Closes Highway.” TahoeDailyTribune.com, December 31, 2010. https://www.tahoedailytribune.com/news/winter-stormknocks-out-power-and-closes-highway/.) Only during July and August does the City of South Lake Tahoe not typically receive snowfall. Figure 4-28 and Figure 4-29 show the average monthly snowfall and average monthly snowfall days at South Lake Tahoe. From December to April, at least one-third of the time throughout a given month receives snowfall at South Lake Tahoe.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-118 Figure 4-28 Average Monthly Snowfall at South Lake Tahoe Sources: https://www.weather-us.com/en/california-usa/south-lake-tahoe-climate; NOAA NWS; World Climate Figure 4-29 Average Monthly Snowfall Days at South Lake Tahoe Sources: https://www.weather-us.com/en/california-usa/south-lake-tahoe-climate; NOAA NWS; World Climate High snow loads can cause damage to buildings and roofs. Snow removal costs can impact budgets significantly. In addition, heavy snowfall during winter can lead to flooding or landslides during the spring if the area snowpack melts too quickly.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-119 Previous Occurrences
As shown in Table 4-34, winter storms and heavy snow hazards are not uncommon since 1950, there have also been 247 reports of winter storms that caused around $665,000 property loss in combination with three deaths and five injuries in El Dorado County (NOAA NCEI 2021). It is assumed that these winter storms and heavy snow events across El Dorado County are likely to have also affected the City of South Lake Tahoe at some point or to some extent.

As shown in Table 4-34, there have been more than 500 reports of heavy snow that led to more than $1.675 million property loss together with one death and four injuries (NOAA NCEI 2021). It is assumed that these heavy snow hazard events across El Dorado County are likely to have also affected the City of South Lake Tahoe at some point or to some extent.

Probability of Future Occurrences
Highly likely – Given that climatic factors will continue influencing the weather and climate at the City and based on historical data, it is highly likely that both winter storms and heavy snow events are highly likely to occur in the future.

Related Hazards
The most significant secondary hazards associated with severe winter storms and heavy snow are avalanches. Since 1950, there have been 18 avalanches that resulted in nine deaths and 12 injuries. Also, since 1950, more than 500 reports of heavy snow that lead to more than $1.675 million property loss together with one death and four injuries, and 247 reports of winter storms that cause around $665,000 property loss together with three deaths and five injuries.

Climate Change Considerations
According to recent findings published by Environmental Defense Fund, more periodic and high-intensity snowfall and rain events during winter storms is an expected outcome of climate change, because a warmer planet is evaporating more water into the atmosphere. The added moisture means more precipitation in the form of heavy snowfall or precipitation in the form of rain rather than snow due to warmer temperatures. Moreover, climate change may be expected to lead to more frequent extreme weather conditions in the future (Environmental Defense Fund 2021). Because the historical average snow water equivalent is expected to decline over time in the Tahoe Basin, the effect will be reduced snowpack levels even though there will still be periodic heavy snowfall and rain events. Figure 4-30 shows the monthly averages of projected snow water equivalent values for South Lake Tahoe under both RCP 4.5 (low-emissions scenario) and RCP 8.5 (high-emissions scenario). When using CanESM2 – the average simulation, under both emissions scenarios, the annual mean of snow water equivalence is projected to drop by the end of the century.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-120 Figure 4-30 Predicted Future Snow Water Equivalence under Low-emission and High-emission Scenarios for South Lake Tahoe Source: Cal-Adapt 2021
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-121 Vulnerability Assessment
Property
Buildings are considered to be exposed to severe winter weather, but structures in poor condition may risk the most damage. Vulnerability is influenced both by architecture and types of construction material and should be assessed on a building-by-building basis. Those that are located under or near overhead lines or large trees may be vulnerable to falling ice or may be damaged in the event of a collapse.

People
Winter storms, and heavy snow and high winds are similar. The combination of heavy snow and strong winds can easily knock out the City’s power supply. Downed trees and fallen power lines might occur.

Transportation around the City can be affected, with road closures interrupting movement. Damages to homes, businesses, and government buildings are possible. Fatalities may occur, posing a fire and/or electrocution threat and can result in fatalities and injuries can also occur. Electrical power outages can also happen. The interruption. Interruption of power causes the loss of people to lose electricity, which affects the heating of homes and water, pumping of water, refrigeration, lighting, computing, as well as the loss of communication systems like television and the internet. Power outages can be life-threatening to those dependent on electricity for life support. Vulnerable populations including the elderly, lowincome and/or linguistically isolated populations can face worse isolation and exposure during severe winter weather events and also face secondary effects of the hazards. Additionally, individuals engaged in outdoor recreation during a severe winter event may be difficult to locate and rescue.

Severe winter storms produce snow and ice and thus create problems and challenges to transportation.

Uprooted trees and fallen limbs also pose possible hazards to roadways, structures, vehicles, and people.

Roads are closed or are open only to vehicles that are properly equipped. Productivity is also lost due to the increased time it takes to go from one point to another. When roads are closed for avalanche prevention or snow removal, drivers who must wait by the roadside are put at an increased risk because of being stranded in route. Stranded commuters may also be vulnerable to carbon monoxide poisoning or hypothermia.

Critical Facilities and Infrastructure
All critical facilities and infrastructure are likely exposed to severe winter weather. The most common problems associated with this hazard are utility losses. Downed power lines can cause blackouts, leaving large areas isolated. Phone, water, and sewer systems may not function. Roads may become impassable due to ice or snow. There are limited county roads and highways that are available to move people and supplies throughout the region. Also, snowstorms can significantly impact the transportation system and the availability of public safety services. Of particular concern are roads providing access to isolated areas and vulnerable populations. Prolonged obstruction of major routes can disrupt the shipment of goods and other commerce. Large, prolonged storms can have negative economic impacts on an entire region.

In addition, government offices may be closed or subject to reduced schedules. Public schools also may be closed or on a delayed start schedule. Structures are put at an increased risk due to increased snow loads on roofs, and the increased threat of falling trees or power lines. Power and phone lines may be knocked over and electrical power might be lost. Downed power lines pose a fire and/or electrocution threat. Uprooted trees and fallen limbs pose possible hazards to roadways, structures, vehicles, and people. Extremely violent windstorms might also damage large tracts of commercial forest, causing economic losses to the forest products industry and recreation. 618
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-122 Economy
Due to electrical power outages and interruption of power caused by winter storms, heavy snow and high winds, businesses lose the use of cash registers, gasoline pumps, restaurant kitchen appliances, leading to potential operational threats to industries including commerce, tourism, and recreation industries.

Economic impacts primarily stem from snow removal and restoration activities. Other direct costs affect primarily the financial and insurance category from property damage. Disruptions to business operations resulting in short-term regional or local impacts may occur. (U.S. Department of Homeland Security 2014) In addition, extremely violent windstorms might also damage large tracts of commercial forest, causing economic losses to the forest products industry and recreation.

Historic, Cultural and Natural Resources
The natural environment is not typically directly damaged by winter storms, except for the secondary hazard of avalanches. As noted previously, older, historic buildings could potentially be more vulnerable to roof and structural damage from heavy snow.

Future Development
Continued development implies continued population growth, which raises the number of individuals potentially exposed to severe weather. Due to the frequency of severe winter storms, and heavy snow and high winds, individual citizens, families, and businesses of the City need to be prepared to address severe weather events when they occur. It is recommended that citizens, families, and businesses have a plan, store extra supplies of food and water, as well as other related, supplied supplies such as flashlights, batteries, firewood and have a battery-operated radio within their home or business. Other protective measures for both existing and future development include trimming tree limbs and securing potentially windblown possessions when not in use. Meanwhile, public education efforts should continue to help the population understand the risks and vulnerabilities of outdoor activities, property maintenance, and regular exposures during periods of severe weather.

Risk Summary
• Ten out of 12 months are months with snowfall for the City and the City receives around 190.81 inches of snow annually.
• Reports of winter storms, and heavy snow and high winds-related hazard events are not uncommon in the City. These hazards have resulted in significant economic loss, mortality, and injuries. • Severe weather can severely damage the City’s property, infrastructure and economy as well as affect the lives of the City’s citizens.
• Climate change is expected to introduce more snowfall during winter storms but result smaller snowpack and earlier snowmelt. Climate change may be expected to cause more frequent extreme weather conditions in the future.
• Overall, the significance of winter storms and heavy snow weather is High.

4.3.9 Severe Weather: Thunderstorms/Hail/Lightning/High Winds and Tornado Hazard Description
Thunderstorms are formed from a combination of moisture, rapidly rising warm air, and a force capable of lifting air, such as warm and cold fronts or a mountain. Thunderstorms may occur alone, in clusters, or in lines. As a result, several thunderstorms can affect one location in the course of a few hours. A thunderstorm can produce lightning, thunder, and rainfall and may also lead to the formation of tornadoes, hail, downbursts, and microbursts of wind. Electricity can be interrupted by lightning strikes 619
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-123 and property damage can occur if hailstones reach a large diameter. As a result, recreational activities can also be interrupted. Playing fields and pools and beaches may be temporarily evacuated, and hot springs facilities may close for safety reasons. During the summer, climatic factors combine to promote the development of thunderstorms. As heated air from lower elevations rises and rapidly cools, intense thunderstorm cells can develop in South Lake Tahoe's high elevation landscape. These thunderstorms often generate hailstones as large as golf balls. Severe thunderstorms also introduce lightning hazard events.

Hail forms on condensation nuclei such as dust or ice crystals, when supercooled water freezes on contact.

In clouds containing large numbers of supercooled water droplets, these ice nuclei grow quickly at the expense of the liquid droplets. The hail grows increasingly larger. Once a hailstone becomes too heavy to be supported by the storm’s updraft it falls out of the cloud. Hailstones are usually from the size of a pea to the size of a golf ball. The NWS in Reno issues Severe Thunderstorm Warnings for thunderstorms capable of producing large hail (above 1-inch diameter) and/or high winds (above 58 mph).

Lightning is an electrical discharge between positive and negative regions of a thunderstorm. A lightning flash is composed of a series of strokes with an average of about four strokes per flash. The length and duration of each lightning stroke vary but typically average about 30 microseconds.

As mentioned above, thunderstorms can form downbursts and microbursts of wind. Downbursts may reach speeds of 125 mph while microbursts are more concentrated and can reach up to 150 mph.

Typically both last 5 to 7 minutes. Meanwhile, the winter storms produce periods of high winds in the Sierra Nevada. Winds of 40-60 miles mph that typically precede the snow portion of a winter storm are the most common starting from late fall through spring. Strong winds are the direct result of large differences in atmospheric pressure from the storm itself and the surrounding environment. Winds can be further enhanced in localized areas on the leeward side of mountain ranges in what is called a downslope windstorm. Wind gusts in these situations can exceed 80 mph, reaching nearly 100 mph in the most extreme cases.

Location
Extensive – Thunderstorm events are not uncommon in the City, especially during summer months, so are the related lightning events. Hail events are also common in the City. Figure 4-31 shows areas within the Planning Area that have historically experienced hail events. High winds events introduced by either thunderstorms or winter storms can impact all areas of the City during any month of the year. The surrounding mountainous landscape along the Sierra Nevada crest also promotes the formation of wind. 620
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-124 Figure 4-31 Hail Events in South Lake Tahoe
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-125 Extent (Magnitude/Severity)
Limited – Although thunderstorm events by themselves may not create significant damage or danger to the City, hail, lightning and high winds events that happen together with thunderstorm events can all have damaging effects. Thunderstorms that are formed in the City often produce hail as large as golf balls (City of South Lake Tahoe 2008).

Lightning
Lightning is measured by the Lightning Activity Level (LAL) scale, created by the NWS to define lightning activity into a specific categorical scale. The LAL is a common parameter that is part of fire weather forecasts nationwide. The City is at risk to experience lightning in any of these categories. The LAL is reproduced in Table 4-36.

Table 4-36 Lightning Activity Level Scale
LAL 1 No thunderstorms.

LAL 2 Isolated thunderstorms. Light rain will occasionally reach the ground. Lightning is very infrequent, 1 to 5 cloud to ground strikes in a five-minute period.

LAL 3 Widely scattered thunderstorms. Light to moderate rain will reach the ground. Lightning is infrequent, 6 to 10 cloud to ground strikes in a five-minute period.

LAL 4 Scattered thunderstorms. Moderate rain is commonly produced.

Lightning is frequent, 11 to 15 cloud to ground strikes in a fiveminute period.

LAL 5 Numerous thunderstorms. Rainfall is moderate to heavy. Lightning is frequent and intense, greater than 15 cloud to ground strikes in a five-minute period.

LAL 6 Dry lightning (same as LAL 3 but without rain). This type of lightning has the potential for extreme fire activity and is normally highlighted in fire weather forecasts with a Red Flag warning.

Source: NWS
Lightning is a common factor in new wildfire starts in the Sierra Nevada, though no specific information is available for South Lake Tahoe. (Douglas County 2019 HMP). The relationship of lightning to wildfire ignitions in the City and El Dorado County increases the significance of this hazard. Lightning strikes are more likely at higher elevations, such as mountain peaks, and may pose a threat to hikers, climbers, and other recreational users.

Hail
The NWS classifies hail by diameter size, and corresponding everyday objects to help relay scope and severity to the population. Table 4-37 indicates the hailstone measurements utilized by the NWS.

Table 4-37 Hail Measurements
Average Diameter Corresponding Household Object
.25 inch Pea
.5 inch Marble/Mothball
.75 inch Dime/Penny
.875 inch Nickel

1.0 inch Quarter

1.5 inch Ping-pong ball

1.75 inch Golf Ball
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-126 Average Diameter Corresponding Household Object

2.0 inch Hen Egg

2.5 inch Tennis Ball

2.75 inch Baseball

3.00 inch Teacup

4.00 inch Grapefruit

4.5 inch Softball
Source: NWS
There is no clear distinction between storms that do and do not produce hailstones. Nearly all severe thunderstorms probably produce hail aloft, though it may melt before reaching the ground. Multi-cell thunderstorms produce many hailstones, but not usually the largest hailstones. In the life cycle of the multi-cell thunderstorm, the mature stage is relatively short so there is not much time for the growth of the hailstone. Supercell thunderstorms have sustained updrafts that support large hail formation by repeatedly lifting the hailstones into the very cold air at the top of the thunderstorm cloud. In general, hail two inches (5 cm) or larger in diameter is associated with supercells (a little larger than golf ball size which the NWS considers to be 1.75 inches.). Past hail events in the City produced hail ranging from 0.75 inches (penny) to 0.88 (nickel) in size. Non-supercell storms are capable of producing golf ball-size hail.

In all cases, the hail falls when the thunderstorm’s updraft can no longer support the weight of the ice.

The stronger the updraft the larger the hailstone can grow. When viewed from the air, it is evident that hail falls in paths known as hail swaths. They can range in size from a few acres to areas 10 miles wide and 100 miles long. In some instances, piles of hail have been so deep that snowplows were required to remove them, and occasionally hail drifts have been reported. Severe hailstorms can be destructive to property. Vehicles, roofs of buildings and homes, and landscaping are the most commonly damaged by hail. Hail has been known to cause injury to humans and occasionally has been fatal.

High Winds
High winds, often accompanying severe thunderstorms, can cause significant property and crop damage, threaten public safety, and have adverse economic impacts from business closures and power loss. High winds events, combined with other natural hazards such as hail, disrupt daily activities, cause damage to buildings, and structures, and increase the potential for other hazards, and sometimes can be lifethreatening. Flying debris can result in injuries and deaths. High winds events during winter times can cause damage, close highways (blowing snow), and induce avalanches. High winds events can also cause trees to fall, particularly those killed by pine beetles or wildfire, creating a hazard to property or those outdoors. Refer to Table 4-38 and the Beaufort Wind Scale that describes the visible condition various wind speeds can be experienced in a community.

Table 4-38 Beaufort Wind Scale
Wind Speed
(mph)
Description—Visible Condition
0 Calm; smoke rises vertically
1-4 Light air; direction of wind shown by smoke but not by wind vanes 4-7 Light breeze; wind felt on face; leaves rustle; ordinary wind vane moved by wind
8-12 Gentle breeze; leaves and small twigs in constant motion; wind extends light flag
13-18 Moderate breeze; raises dust and loose paper; small branches are moved 19-24 Fresh breeze; small trees in leaf begin to sway; crested wavelets form on inland water
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(mph)
Description—Visible Condition
25-31 Strong breeze; large branches in motion; telephone wires whistle; umbrellas used with difficulty
32-38 Moderate gale whole trees in motion; inconvenience in walking against wind
39-46 Fresh gale breaks twigs off trees; generally, impedes progress 47-54 Strong gale slight structural damage occurs; chimney pots and slates removed
55-63 Whole gale trees uprooted; considerable structural damage occurs 64-72 Storm very rarely experienced; accompanied by widespread damage 73+ Hurricane devastation occurs
Source: NWS
Previous Occurrences
Thunderstorms/Lightning
It is important to note that County or City-level thunderstorm and lightning data are not available, however, as noted above, thunderstorm events are not uncommon in the City, especially during summer months, so are the related lightning events.

Hail
Hail events are common in the City. Figure 4-32 shows that different areas within the City’s Planning Area, the City’s SOI, and other areas in the vicinity have historically experienced hail events. Several hail events during which quarter and even golf ball-sized hailstones happened in recent years. As shown in Table 4-37, since 1950, there have been 20 reports of hail events that caused around $1,000 property loss and $586,000 crop loss in combination with five injuries in El Dorado County. (NOAA NCEI 2021). It is assumed that these hail hazard events across El Dorado County are likely to have also affected the City of South Lake Tahoe at some point or to some extent.

High Winds
As shown in Table 4-37, high winds events are not uncommon in El Dorado County. It is assumed that these high winds events across El Dorado County are likely to have also affected the City at some point or to some extent. Since 1950, there have been 173 reports of high winds that led to $13.58 million property loss, $48,000 crop loss, together with one death and three injuries.

An example of a severe high winds event in the City was reported on January 19, 2021, which caused multiple power outages and at least two Lake Tahoe ski resorts to shut down. The NWS issued a high wind warning that day, pointing out that gusts over 130 miles per hour are possible over the top of Sierra ridges. (KTLA 2021) Figure 4-33 shows a high winds event that occurred in the southwest of the City in 1981 where there was a wind speed of 56 – 63 knots, which equals around 64 – 72 mph. In addition, in 2015, there was a tornado event that happened near southwest Lake Tahoe, which had a path that led to the north of the City of South Lake Tahoe. The tornado had an intensity of EF0 while the EF-scale ratings range from 0 – 5. Figure 4-34 shows the location and path of this tornado event. 624
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-130 Probability of Future Occurrences
Highly Likely – 20 hail events and 173 high winds events have occurred in El Dorado County over 70 years of recordkeeping, which equates to one hail event every 3.5 years and 2.5 high winds events every year. Moreover, given that climatic factors will continue influencing the weather and climate at the City and based on historical data, thunderstorms, hail, lightning and high winds events are highly likely to occur in the future. The actual risk to the City is dependent on the nature and location of any given hazard event.

The most significant secondary hazards associated with severe local storms are flash floods, falling and downed trees, landslides, and downed power lines. Rapidly melting snow combined with heavy rain can overwhelm both natural and manmade drainage systems, causing overflow and property destruction.

Violent summer thunderstorms can result in localized dry-mantle flash-flooding events that threaten life and property. Landslides occur when heavy and prolonged rains can cause soil on slopes to becomes oversaturated and ultimately fail, which results in landslides that can block roads and affect transportation infrastructure. Wildfires can occur as a result of lightning strikes and can be exacerbated and unpredictable as a result of high winds making them difficult to suppress. High winds in the winter can turn a small amount of snow into a complete white-out and create drifts in roadways. Debris carried by high winds can also result in injury or damage to property.

Climate Change Considerations
As the atmosphere warms due to climate change, the increased heat in the atmosphere provides more energy for severe storms. The frequency of severe weather events has increased steadily over the last century. Historical data shows that the probability of severe weather events increases in a warmer climate.

The changing hydrograph caused by climate change could have a significant impact on the intensity, duration and frequency of storm events.

Figure 4-34 shows the estimated intensity (return level) of extreme precipitations events which are exceeded on average once every 20 years (return period) and how it changes in a warming climate over historical, mid-century and late-century time periods, based on the Cal-Adapt webtool mentioned in 4.1.4 Climate Change Consideration. Under both RCP 4.5 (low-emissions scenario) and RCP 8.5 (high-emissions scenario), Precipitation level will increase throughout the century. When using the average simulation, precipitation will increase from around 5 inches to almost 8 inches by 2099 under the low-emissions scenario and will increase from around 5 inches to almost 9 inches by 2099 under the high-emissions scenario. For these graphs that were exported from Cal-Adapt, extreme precipitation events are defined as days during a water year (Oct–Sep) with 2-day rainfall totals above an extreme threshold of 0.88 inches. 627
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-131 Figure 4-34 Predicted Future Changes in Intensity of Extreme Precipitation Events – under Cal-Adapt’s low-emissions and highemissions scenarios for South Lake Tahoe Source: Cal-Adapt 2021
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 4-132 As for wind, studies referenced in California’s Fourth Climate Assessment indicated that extreme fire weather, particularly in the form of hot and dry winds, can strongly influence shrub-land fire regimes.

Strong winds have also been associated with severe forest fires in California, meaning climate change impacts on wind patterns may also affect forest health and wildfire susceptibility. Lastly, other ongoing research compiled has resulted in different conclusions on the effect of climate change on wind regimes, particularly extreme wind events, such as the Santa Ana and Diablo winds that created some of the most devastating wildfires (California Natural Resources Agency 2018a). At this time, these changing factors are not well understood and are still being incorporated into state and regional research and risk analysis.

Vulnerability Assessment
Property
All property is vulnerable during thunderstorms, wind, and hail events, but properties in poor condition may risk the most damage. Generally, the damage is minimal and goes unreported, however, numerous high wind, strong wind, and tornado events have been reported in El Dorado County amounting to $20,445,000 in damage over the past 71 years, which translates to approximately $287,957 in annualized damages each year (see Table 4-34). Property located at higher elevations and on ridges may be more prone to wind damage. Property located under or near overhead lines or large trees may be damaged in the event of a collapse. Older building stock that was built according to older code standards could be highly vulnerable.

Wind pressure can create a direct and frontal assault on a structure, pushing walls, doors, and windows inward. Conversely, passing currents can create lift and suction forces that act to pull building components and surfaces outward. The effects of winds are magnified in the upper levels of multi-story structures. As positive and negative forces impact the building’s protective envelope (doors, windows, and walls), the result can be roof or building component failures and considerable structural damage. In short, all buildings are exposed to thunderstorms, wind, hail and high winds hazards while the frequency and degree of damage will depend on specific locations.

People
The entire City is exposed to some extent to thunderstorms, hail, lightning and high winds events. Certain areas are more exposed due to geographic location and local weather patterns. Populations living at higher elevations with large stands of trees or power lines may be more susceptible to wind damage and power outages, while populations in low-lying areas are at risk for possible flooding.

Vulnerable populations are the elderly, low-income or linguistically isolated populations, people with lifethreatening illnesses, and residents living in areas that are isolated from major roads. Power outages can be life-threatening to those dependent on electricity for life support. Isolation of these populations is a significant concern. These populations face isolation and exposure during thunderstorms, hail, lightning and high winds events and could suffer the secondary effects of the hazard. Hikers and climbers in the area may also be more vulnerable to severe weather events. Visitors to the area may not be aware of how quickly a thunderstorm can form in the mountains.

Critical Facilities, and Infrastructure
Transportation infrastructure can be affected by thunderstorms, hail, lightning and high winds events, mostly associated with secondary hazards. Landslides caused by heavy prolonged rains can block roads.

High winds can cause significant damage to trees and power lines, blocking roads with debris and cutting off transportation access, isolating population, and disrupting ingress and egress. Of particular concern are roads providing access to isolated areas and the elderly, especially given that limited local roads and 629
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Severe windstorms and downed trees can create serious impacts on power and above-ground communication lines. Loss of electricity and phone connection would leave certain populations isolated because residents would be unable to call for assistance. Lightning events in the City can have similar destructive effects on power, communication, and information systems. Failure of these systems would have cascading effects throughout the City and could disrupt critical facility functions. Downed power lines can cause blackouts, leaving large areas isolated.

Economy
The economic impact of a severe thunderstorm is typically short-term. Lightning and high winds events can cause power outages and fires. Generally, long-term economic impacts center more around hazards that cascade from a severe thunderstorm, including wildfires ignited by lightning, and flooding. In general, all severe thunderstorms pose a risk to the tourism economy and outdoor recreation industry in the City.

These events can disrupt travel into and out of the City and create perilous conditions for residents and tourists.

Historic, Cultural and Natural Resources
The environment is highly exposed to lightning, winds, and hail. Natural habitats such as streams and trees risk major damage. Prolonged rains can saturate soils and lead to slope failure and potentially landslide events. Flooding events can produce river channel migration or damage riparian habitat. Large swaths of tree blowdowns can occur, particularly in the bark beetle-killed forests prevalent in the Lake Tahoe Basin Management Unit.

Future Development
Future development will be exposed to thunderstorms, hail, lightning and high winds events. The ability to withstand impacts lies in sound land use practices and consistent enforcement of codes and regulations for new construction. Adopting codes and land use policies that are equipped to deal with the impacts of severe weather events and address secondary impacts such as floods and landslides would prepare the City well to manage the impacts of severe weather. Other protective measures for both existing and future development include trimming tree limbs and securing potentially windblown possessions when not in use.

Meanwhile, continued development implies continued population growth, which raises the number of individuals potentially exposed to severe weather. Individual citizens, families, and businesses of the City need to be prepared to address severe weather events when they occur. It is recommended that citizens, families, and businesses have an emergency preparedness plan, such as storing extra supplies of food and water, as well as other related supplies such as flashlights, batteries, firewood and have a battery-operated radio within their home or business. In addition, public education efforts should continue to help the population understand the risks and vulnerabilities of outdoor activities, property maintenance, and regular exposures during periods of severe weather.

Risk Summary
• There have been 193 recorded hail and high winds events in the City of South Lake Tahoe since 1950, resulting in over $14,214,500 property and crop damages, or approximately $200,204 in damages each year.
• Hail and high winds events have caused eight injuries and one death since 1950. 630
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-134 • The combination of high wind, strong wind, and tornado events in El Dorado County resulted in $20,445,000 in damage over the past 71 years, which translates to approximately $287,957 in annualized damages each year.
• Severe weather can severely damage the City’s property, infrastructure and economy as well as affect the lives of the City’s citizens.
• Climate change may be expected to cause more frequent extreme weather conditions in the future. • Overall, the significance of severe weather: thunderstorms/hail/lightning/high winds is Medium.

4.3.10 Wildfire
Hazard Description
Wildfires are a significant concern throughout California as the frequency, intensity, and size of wildfires has increased throughout the State over the last 25 years. Wildfires are uncontrolled fire events that occur most often on undeveloped land and typically require fire suppression to prevent damage to the human environment. They are caused by natural sources, such as lightning, but more commonly by humansources of ignition such as discarding of cigarettes, arson, vehicle fires, abandoned campfires, and from electrical infrastructure malfunction.

Wildfires starting in areas surrounding the City’s Planning Area have the potential to create direct and indirect impacts to people and property within the City’s boundary. Wildfires can directly expose people and property to radiant heat, flying embers, and flames that result in the risk of injury and death, and the destruction or damage to structures and critical infrastructure. Wildfires can also result in impacts to natural and cultural resources and forest health, depending on the severity of the wildfire. Wildfire risk is predominantly associated with wildlands and less densely populated rural areas but can also spread directly or indirectly (through blowing embers) into more densely populated areas, such as the Planning Area. Smoke emissions from wildfire can also impact communities. For example, smoke emissions emanating from the 2021 Caldor Fire, occurring miles away from the City, led to extended periods of poor air quality, traffic visibility issues, and public health concerns, creating impacts to the local economy and the community’s quality of life.

Fire conditions arise from a combination of high temperatures, low humidity and rainfall, high winds, and an accumulation of vegetation and surface fuels (litter, duff, accumulated dead vegetation). In the City, wildfires have occurred in vegetated areas within and outside of the Planning Area. Generally, in this area, the fire season extends from June through October of each year during the hot, dry months, although trends associated with climate change indicate that the fire season statewide is expanding to earlier in the spring and later into the fall.

Wildfires can generate secondary effects that can result in economic losses related to timber harvesting and reductions in tourism. Wildfires can also impact electrical power transmission infrastructure, water storage contamination, and increased runoff and slope failure due to loss of vegetation and weakened soils. The right-of-way along transmission and distribution lines need to be cleared following wildfires and usually power poles need to be replaced. Wildfires that produce high heat intensity can impact soils and increase runoff, and in turn impact water quality in Lake Tahoe and other regional lakes. Landslides and other forms of slope failure and debris flows often follow wildfire events.

Geographic Location
Extensive – Most of the geographic areas in the City Planning Area are at risk of wildfire hazards. Nearly all areas within the City’s SOI is designated as WUI (see Figure 4-35) according to California Department of Forestry and Fire Protection (CALFIRE) and hence wildfire hazard can be categorized as “extensive.” The 631
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-135 WUI is a zone of transition between unoccupied natural lands and the human occupied built environment.

The WUI includes three components: human presence, wildland vegetation, and a distance that represents the potential for effects (e.g., wildland fire and human activity) to extend beyond boundaries and impact neighboring lands. The WUI is not a designation of potential wildfire severity, but rather mapped description of an area where urban development meets undeveloped lands at risk of wildfires. The WUI zones within and surrounding the City are shown in Figure 4-35 and include three zones: 1) dense housing adjacent to vegetation that can burn in a wildfire (also known as the WUI), 2) Wildland Urban Intermix is housing development interspersed in an area dominated by wildland vegetation subject to wildfire, and 3) Wildfire Influence Zone is wildfire susceptible to vegetation up to 1.5 miles from WUI or Wildland Urban Intermix zones. A lack of defensible space management puts homes and structures at increased wildfire risk. Additionally, homes and structures that are not retrofitted with ignition-resistant construction materials can be at increased vulnerability to wildfire heat and embers.

In California, fire prevention and protection activities are divided into different responsibility areas, including Local Responsibility Area (LRA), State Responsibility Areas (SRA), and Federal Responsibility Area (FRA). LRAs include incorporated cities, urban regions, agriculture lands, and portions of the desert where the local government is responsible for fire prevention activities. SRAs are those areas where the State of California is responsible for fire protection, and FRAs are those areas where the federal government is responsible for fire protection. The City’s Planning Area and surrounding vicinity includes each type of responsibility area (see Figure 4-36). The fire prevention and protection resources’ ability to suppress wildfires is a key factor that affect wildfire impacts and federal, state, and local agencies that coordinate and share resources, such as the TFFT are more effective at managing wildfires and protecting the community.

CALFIRE’s Fire and Resource Assessment Program (FRAP) is charged with mapping and classifying the severity of fire hazards in California. Per this requirement, FRAP has produced fire hazard severity zone (FHSZ) maps using science-based wildfire behavior modeling techniques to classify moderate, high, and very high FHSZs within SRAs. FHSZ maps consider fire history, potential fuel (live and dead vegetation), predicted flame length, blowing embers, topography, weather (temperature, humidity, precipitation, and wind), and represent the potential of an area burning over a 30-year to 50-year time horizon. According to California Government Code (i.e., Sections 51177, 51178, 51178.5, 51179) “very high fire hazard severity zones” (VHFHSZs) within LRAs are delineated by CALFIRE and reviewed by local communities and fire authorities – with subsequent ordinances adopted by local authorities. VHFHSZs are based on fuel loading, slope, fire weather, and other relevant local factors including areas where winds have been identified as a major driver of wildfire spread. Additional information on the FRAP FHSZ map are explained in more detail in the Extent (Magnitude/Severity) section below. Figure 4-36 shows zones designated as VHRHZ within the City’s Planning Area and other FHSZs within the SOI relative to the City’s LRA and SRAs. The figure also depicts CALFIRE’s final recommendations for “very high” FHSZs within the City. In general, most lands within the City can be classified as having a very high fire hazard severity potential.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-139 Extent (Magnitude/Severity)
Critical - The frequency and severity of wildfires in El Dorado County (and City) has changed over the past 50 years, and particularly over the past 20 years as indicated by the recent occurrences of wildfires in the region (e.g., 2021 Caldor Fire). As the wildfires increase in burn intensity and size, the number and proportion of susceptible structures and human population also increases, which results in a potential increased in magnitude and severity of impact. Potential losses from wildfires include human life, structures and other improvements, natural and cultural resources, quality and quantity of water supplies, cropland, timber, recreational opportunities, and impacts to the community’s way of life. Economic losses could also result from reduced recreation opportunities, tourism and visitation and generally impacted economic sectors. Smoke, ash, and air pollution from wildfires can be a severe health hazard. In addition, catastrophic wildfire can create favorable conditions for other secondary hazards such as flooding, landslides, and erosion during the rainy season. Typically, the potential for significant damage to life and property exists in areas or zones designated as WUIs, where development is adjacent to densely vegetated area. Wildfire potential in the City can vary based on the sloped topography, vegetation, climate, and varying fire-prone landscapes in the City’s neighborhoods.

Generally, there are three major factors that sustain wildfires and predict a given area’s potential to burn.

These factors are fuel, topography, and weather, as described below. • Fuel – Fuel is the material that feeds a fire and is a key factor in wildfire behavior. Fuel is generally classified by type and by volume. Fuel sources are diverse and include everything from dead tree leaves, twigs, and branches to dead standing trees, live trees, brush, and cured grasses. Manmade structures, such as homes and other associated combustibles are also fuel sources. The type of prevalent fuel directly influences the behavior of wildfire. Fuel is the only factor that is under human control. Fuel types within and surrounding the City vary but generally consist of mixed conifer and fir forests, alder-willow riparian habitat, upper montane mixed shrub, basin sagebrush, wet meadows, and lakes and waterways. Mixed conifer and fir forest are typically the highest fuel sources in the City and include primarily Jeffery Pine (Pinus jefferyi), lodgepole pine (Pinus contorta ssp), Sugar pine (Pinus lambertiana), and western white pine (Pinus monticola) mixed with mountain sagebrush (Artemisia tridentata ssp.), antelope bitterbrush (Purshia tridentata), Greenleaf manzanita (Arcotostaphylos patula), and huckleberry oak (Quercus vacciniifolia) vegetation communities. • Topography – An area’s terrain affects its susceptibility to wildfire spread. Both fire intensity and rate of spread increase as slope increases due to the tendency of heat from a fire to rise via convection.

The arrangement of vegetation throughout a hillside can also contribute to increased fire activity on slopes.
• Weather – Weather components such as temperature, relative humidity, wind, and lightning affect the potential for wildfire. High temperatures and low relative humidity dry out fuels that feed wildfires, creating a situation where fuel will more readily ignite and burn more intensely. Thus, during periods of drought, the threat of wildfire increases. Wind is the most treacherous weather factor. The greater a wind, the faster a fire will spread and the more intense it will be. Lightning can also ignite wildfires, often in difficult to reach areas for firefighters.

Wildfires in the area surrounding the City have ranged from fires that burned less than one acre in size to the Angora Fire in 2007 that burned 3,100 acres and destroyed up to 280 structures. However, fires in the broader region (El Dorado County and bordering counties such as Alpine County in California and Douglas County in Nevada) in recent years have resulted in much larger and damaging wildfires and the loss of property as well as human injuries or even deaths. The smoke, ash, and air pollution from wildfires are also severe health hazards particularly for sensitive populations including the elderly, children, and people with respiratory and cardiovascular diseases. Wildfires can also threaten the health and safety of 636
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-140 those fighting the fires, so the overall magnitude or severity of fires can be wide-reaching and incur many types of impacts. Overall, wildfire severity can usually be quantified in terms of acres burned during an event, number, and cost of properties/structures damaged (including critical facilities), money lost from disruption of services, and population affected by the fires (e.g., people displaced, injured, or killed). A wildfire in the City’s Planning Area could result in catastrophic impacts considering the population size, natural resource and recreational values, relatively old age of housing stock (not as resilient to wildfire effects), and property value.

CALFIRE wildfire threat analysis and associating mapping efforts provide a measure of vegetation and fuel conditions and fire potential, representing the relative likelihood of “damaging” or the difficulty to control or suppress wildfire occurring for a given area. CALFIRE’s fire threat assessment can be used to assess the potential for impacts on various assets and values susceptible to fire. Impacts are more likely to occur and/or be of increased severity for the higher threat classes. Fire threat is a combination of two factors: 1) fire probability, or the likelihood of a given area burning, and 2) potential fire behavior (e.g., potential flame length or hazard). These two factors are combined to create five threat classes ranging from low to extreme. Figure 4-38 shows the distribution of fire threat according to CALFIRE throughout the City’s Planning Area. The majority of City’s SOI and surrounding area consist of ‘non-fuel’ (low), ‘moderate,’ ‘high,’ and ‘very high’ fire threat classification – ‘moderate’ indicating improved potential to control or suppress a fire. The western (near Fallen Leaf area, Tahoe/Gardner Mountain and Twin Peaks) and southern portions of the City’s Planning Area, particularly south of the developed areas (within the Caldor Fire perimeter) shows potentially elevated wildfire intensity (i.e., very high fire threat) and difficulty to suppress. The information shown in Figure 4-38 will need to be updated to reflect changes in vegetation and fuels conditions affected by the 2021 Caldor Fire.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-142 Previous Occurrences
Since 1915 there have been 180 fires within 30 miles of South Lake Tahoe. While most fires are small, there have been 28 fires over 1,000 acres (Figure 4-39). Ten of those fires occurred in the last 20 years.

Prior to the King Fire in 2014, the largest fire recorded in the area (but outside of the Basin) was 22,000 acres in 1992 (Cleveland Fire). Several fires were between 15,000 and 20,000 acres since 1950 but the recent King, Tamarack, and Caldor fires are many orders of magnitude larger than the typical large historical wildfire. Below is a summary of the notable fires in the greater South Lake Tahoe Region:
• Caldor Fire, 221,835 acres, started Aug 14, 2021. Roughly 12,000 acres of the fire occurred within the Lake Tahoe watershed, near Meyers and South Lake Tahoe. As of October 21, 2021, it was 100% contained. It destroyed 782 structures and damaged another 8 (CALFIRE 2021). The Caldor Fire resulted in the evacuation of the City and all communities within the SOI for approximately 10 days (depending on a neighborhood’s proximity to active fire). The fire directly threatened structures in the City and structure within the SOI (CALFIRE 2021).
• Tamarack Fire, 68,637 acres, started July 4, 2021. It destroyed 15 structures and damage two more in the Markleeville area.
• Emerald Fire, 176 acres, it started on October 14, 2016. The Emerald Fire started near the Cascade Lake and Emerald Bay area off Highway 89. Wind gusts and sustained wind contributed to the spread of this fire.
• King Fire, 97,685 acres, started September 13, 2014. There were 12 residences and 68 other structures destroyed (NIFC 2014).
• Angora Fire, 3,070 acres, started on June 24, 2007. The Angora Fire destroyed 254 residences, and damaged 35 additional buildings (NFIC 2007).
• Gondola Fire, 643 acres, started on July 3, 2002 – The Gondola Fire was caused by discarded smoking material from the Heavenly gondola. Fire suppression cost close to $3 million, but fortunately no injuries or damage to structures were reported.
• Showers Fire, 288 acres, started on August 19, 2002 – The Showers Fire started when a small plane went down near Elbert Lake near Meiss Meadow, killing a couple from Lafayette, CA. The blaze was estimated to have cost the United States Forest Service (USFS) $1.75 million to suppress.

Probability of Future Occurrences
Likely – The probability of a wildfire event impacting the City Planning Area is between 1 and 10 percent chance of occurrence in the next year or has a recurrence interval of 11 to 100 years. According to data presented by the USDA Forest Service Wildfire Risk to Communities Program (https://wildfirerisk.org/, 2016), populated areas in nearly all other El Dorado County communities, on average, have a greater wildfire likelihood than in South Lake Tahoe. Fire behavior model outputs, based on fuels data updated through 2020 (Pyrologix 2021), estimated that the annual burn probability (ABP) within the City and SOI to range from 0 to 2% (see Figure 4-40), with most areas in the City’s Planning Area of < 1% – meaning that there is generally less than a 1% chance each year that a wildfire will occur within the City’s Planning Area. ABP is the probability that a specific geographic location (e.g., 30m pixel) will experience a wildland fire during a specified time period (i.e., 1 year). It does not say anything about the intensity of fire if it were to occur in that geographic location. Estimates of wildfire likelihood are based on fire behavior modeling across thousands of simulations of possible fire seasons. In each simulation, factors contributing to the probability of a fire occurring, including weather, topography, and ignitions are varied based on patterns derived from observations in recent decades. Wildfire likelihood (or ABP) is not predictive and does not reflect any currently forecasted weather or fire danger conditions. 639
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-145 Climate Change Considerations
Increases in GHG emissions coupled with population growth and development are expected to continue impacting California’s forests and natural resources. Likewise, the effects of climate change will impact wildfire behavior, the frequency of ignitions, fire management, and fuel loads. Increasing temperatures will intensify wildfire threat and susceptibility to more frequent wildfires in the forest that make up large portions of the Planning Area, in addition to wildlands throughout the Tahoe Basin.

Uncertainty exists in how climate change will affect total precipitation, but models suggest that there is a tendency for wetter conditions in the northern part of the state and drier conditions in the south (California Natural Resources Agency 2018). Forests are also sensitive to variable precipitation events, and damaging droughts such as the multi-year event from 2012-2017 contributed to widespread tree mortality as warmer temperatures stressed trees and made them more susceptible to pests and pathogens (California Natural Resources Agency 2018). While the forested areas surrounding the City’s Planning Area consist of wildland intermix and WUI, emerging studies that indicate that hot temperatures and dry winds can influence forest fires in these areas. Studies noted in California’s Fourth Assessment report indicate climate change impacts on wind patterns may strongly affect forests, potentially serving as a trigger mechanism for conversion of forest to other types of vegetation (California Natural Resources Agency 2018). The Fourth Assessment report also notes that in the Sierra Nevada, projected changes in climate are associated with large increases in the area burned by wildfire and the frequency of large fires (California Natural Resources Agency 2018).

Westerling conducted wildfire risk projections based on statistical modeling from historical data of climate, vegetation, population density, and fire history (Westerling 2018). Projected wildfire occurrence (annual area burned) estimates based on different potential climate futures and GHG emission scenarios was summarized and presented in Figure 4-41, Table 4-39, Figure 4-42, and Table 4-40. Projections from these four models can be described as producing the following climate outcomes:
• HadGEM2-ES - A warm/dry future
• CNRM-CM5 - A cooler/wetter future
• CanESM2 - An average future
• MIROC5 - The model simulation that is most unlike the first three for the best coverage of different possibilities.

Each of the climate models responds to variation in GHG emission levels, where greater GHG emissions results in more extreme weather phenomenon. Under a ‘medium’ GHG emissions scenario, projections across all future climate scenario predict that annual area burned in the City could range from 0 to 578 acres between the years of 2020 and 2099 (Figure 4-41, Table 4-39). 642
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-146 Figure 4-41 Modeled Projections of Annual Area Burned (2020 to 2099) for the City of South Lake Tahoe under a Medium GHG Emissions (RCP 4.5) Scenario Source: Westerling 2018 via Cal-Adapt
Table 4-39 shows the projected annual area burned statistics for 2020 to 2099 under the Medium GHG Emissions Scenario for the City for each of the four model projections.

Table 4-39 Projected 2020 to 2099 Annual Area Burned Statistics for a Medium GHG Emissions Scenario for South Lake Tahoe
CanESM2 CNRM-CM5 HadGEM2-ES MIROC5
Hectares (Acres)
Max 95 (235) 234 (578) 127 (314) 175 (432)
Min 1 (2) 0 (0) 3 (7) 0 (0)
Average 22 (54) 39 (96) 31 (76) 35 (87)
Mode 9 (22) 27 (67) 14 (35) 8 (20)
Source: Westerling 2018 via Cal-Adapt
Under a ‘high’ GHG emission scenario, projections across all future climate scenario predict that annual area burned in the City could range from 0 to 3,007 acres between the years of 2020 and 2099 (Figure 4-42, Table 4-40).
0 50
100
150
200
250
2019 2029 2039 2049 2059 2069 2079 2089 2099
Annual Burned Area (Hectares)
Year
CanESM2 CNRM-CM5 HadGEM2-ES MIROC5
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-147 Table 4-40 Modeled Projections of Annual Area Burned (2020 to 2099) for the City of South Lake Tahoe under a High GHG Emissions (RCP 8.5) Scenario Source: Westerling 2018 via Cal-Adapt
Table 4-41 shows the projected annual area burned statistics for 2020 to 2099 under the Medium GHG Emissions Scenario for the City for each of the four model projections.

Table 4-41 Projected 2020 to 2099 Annual Area Burned Statistics under a High GHG Emissions Scenario for South Lake Tahoe
CanESM2 CNRM-CM5 HadGEM2-ES MIROC5
Hectares (Acres)
Max 65 (161) 1,217 3,007) 246 (608) 234 (578)
Min 0 (0) 0 (0) 0 (0) 1 (3)
Average 16.3 (40.2) 100.7 (249) 33.3 (82) 38.7 (96)
Mode 5 (12) 17 (42) 21 (52) 14 (35)
Source: Westerling 2018 via Cal-Adapt
According to the “Integrated Vulnerability Assessment of Climate Change in the Lake Tahoe Basin”, climate change is expected to result in minimum and maximum daily average temperatures increases by the end of the century; variability in precipitation will increase leading to more droughts and storms; increased temperatures that will reduce precipitation falling as snow, which will reduce snowpack levels; and a significant increase in drought stress. The timing of peak runoff will also shift one to five months earlier in the year. Further, by the end of the century, the total area burned by wildfires each decade is projected to be 61% larger than the beginning of the century (Conservancy 2020). These risks are expected to continue to rise due to increased dryness of forest vegetation compounded by the productivity of plants in the spring.

While the CALFIRE program actively collaborates with state, local, and national agencies to reduce climate change impacts, current scientific models expect California will be affected by increased numbers of forest fires with added intensity due to longer warmer seasons, reduced distribution of biodiversity, lack of moisture, changes in ecosystems, drought impacts (e.g., forest pest diseases and continued spread of invasive species), and other such impacts in coming years. Due to these increasingly worsening and 0 200
400
600
800
1000
1200
1400
2019 2029 2039 2049 2059 2069 2079 2089 2099
Annual Burned Area (Hectares)
Year
CanESM2 CNRM-CM5 HadGEM2-ES MIROC5
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-148 recurring issues, wildfire hazards should be carefully studied by the City with regards to future negative effects in or near the City Planning Area related to wildfire risk. For these reasons, climate change would have a “high” influence on wildfire hazards.

Vulnerability Assessment
The City’s wildfire risk and vulnerability is a very high concern as wildfire can damage or destroy property and infrastructure, injure people, or even cause death. Wildfires can affect major transportation roads, such as U.S. Highway 50 (US 50) and SR 89 by impeding commuters to get to and from their destinations (e.g., to Carson Valley, Reno, Bay Area), as well as potentially block emergency responders. These major transportation roads are also key evacuation routes for the City in the event of an emergency.

Populated areas, such as neighborhoods and subdivisions within WUI intermix and interface zones of the City’s Planning Area are predominantly exposed to wildfire from indirect sources (approximately 76% of the City), such as aloft embers or home-to-home ignition (https://wildfirerisk.org/). Areas composed of contiguous vegetation are also directly exposed to wildfire flames and radiant heat.

During the June to October fire season, the dry vegetation and hot sometimes windy weather, combined with an increased visitor population, can result in an increase in wildfire ignitions. Any fire, once ignited, has the potential to quickly become a large, out-of-control fire when dry and windy conditions exist.

Wildfires that prevent essential goods or services from entering or leaving the City could negatively affect local residents and businesses by impacting the local economy and the community’s livelihood (e.g., limited access to jobs, daycare, schools, resources, and residences).

The CALFIRE-produced FHSZs displayed in Figure 4-37 were used to assess general wildfire vulnerability in the City’s Planning Area. Using GIS the City’s parcel layer was used as the basis for the inventory of parcels, while the CALFIRE FHSZs, was used to intersect the parcels and determine general risk based on the severity categories. Centroids were generated for each parcel for simpler overlay analysis, so that a parcel was either “in” a fire hazard severity zone of type “moderate severity,” “high severity,” or “very high severity,” or “out” of any of these FHSZ categories (e.g., in Urban or Non-Wildland/Non-Urban areas). For purposes of this analysis, it was assumed that every parcel with an improved value greater than zero was developed in some way, even those stated as “vacant.” This specification ensures parcels such as rights-ofway (ROW) are discarded for the purposes of determining vulnerability to fire, and to be able to aggregate valuations based on each parcel type (e.g., residential, commercial, public, etc.). The County of El Dorado Assessor’s Office data calculates improved values based on the “annual structure value” which relates to the improvements of the parcel. This was the field used to determine improved values for each parcel.

Once parcels in the form of centroids were categorized by property type, the content values were calculated as follows: a) residential and multi-family properties received contents valued at 50 percent of the parcel improved value; b) commercial and agricultural properties’ contents were valued at 100 percent of the parcel improved value; and c) vacant parcels (if applicable) received 0 percent content values. These valuation assignments are based on FEMA’s methodology for estimating contents within their loss estimation software, Hazus-MH. As previously mentioned, Hazus-MH (for Multi-hazard) is a GIS-based natural hazard analysis tool developed and distributed by FEMA. 645
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-149 People
The residential population of South Lake
Tahoe is approximately 21,814. Potentially vulnerable
populations within the City may have trouble preparing
for and responding to wildfire. Table 4-42 shows
population vulnerability statistics from the most recent five-year rolling survey period of the U.S. Census Bureau ACS for the City. Tourist visitation to the City can
considerably swell the population during weekends,
holidays, and the summer months. Mass evacuations
from the City have the potential to be complicated as
there are four primary routes into and out of the City
limits, including Highway 50 (westbound over Echo
Pass), SR 89 (south), SR 89 (north), and Highway 50
(eastbound over Spooner Summit). Each route or
multiple routes could be impacted by an impending
wildfire. In addition, the vulnerability status of visitors is typically unknown to City officials. Evacuation traffic jams associated the Caldor Fire highlighted potential
opportunities to better understand traffic generation
and distribution (particularly during summer months)
and improve evacuation sequencing and planning by the City.

Table 4-42 Vulnerable Population Statistics for the City of South Lake Tahoe Population Vulnerability Category Number
Percent
Families in Poverty 433 ± 137 9.5% ± 3%
People with Disabilities 3,616 ± 453 16.8% ± 2.1%
People over 65 years old 3,344 ± 409 15.3% ± 1.9%
Difficulty With English Language 1,352 ± 367 6.6% ± 1.8% Households without vehicle 790 ± 210 9.1% ± 2.4%
Mobile Homes 581 ± 173 6.7% ± 6.7%
Source: U.S. Census ACS 2019
Property
All property within the City limits occurs within the “very high” FHSZ. These properties are organized by parcel type and listed in Table 4-43, along with a summary of all improved structure values, contents values, total exposure values (which are the aggregated improved structure values plus the content values), and population at risk. Figure 4-43 displays potential property at risk to wildfires within the City.

Table 4-43 Property Values for Very High FHSZs within LRAs in the City of South Lake Tahoe Fire Zone
Ranking
Parcel Type Improved
Parcels
Improved Structure
Value
Content Value Total Exposure Population
at Risk
Very High
Commercial 382 $534,943,301 $534,943,301 $1,069,886,602 NA Exempt 20 $0 $0 $0 NA
Industrial 198 $174,704,826 $262,057,239 $436,762,065 NA Miscellaneous 38 $49,526,052 $49,526,052 $99,052,104 NA Residential 9,732 $2,405,030,890 $1,202,515,445 $3,607,546,335 22,465 Total 10,370 $3,164,205,069 $2,049,042,037 $5,213,247,106 22,465 Source: Wood Analysis 2021
The Caldor Wildfire evacuation caused hours of traffic
gridlock in the City of South Lake Tahoe along
Highway 50. The City expected the evacuation process
to go slow as residents and visitors evacuated
eastbound towards Nevada given there are few key
routes in and out of the City. This is why City officials started the evacuation phasing process early,
approximately 12 hours after issuing the first
evacuation warning. This also allowed the City to safely evacuate vulnerable populations, and those
experiencing homelessness. The traffic eventually
cleared by 5 p.m. on Monday evening.

Photo Credit: Karl Mondon/Bay Aras News Group 2021
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-150 Figure 4-42 Wildfire Risk to Potential Structures in the City of South Lake Tahoe 647
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-151 Economy
Wildfires can be incredibly destructive depending on the circumstances of the event, particularly the type of resources and populations they affect due to fire size, location, length of the burn, and ongoing or existing weather or hazard conditions. For example, damages to structures and properties are obvious impacts to the economy due to fire, though cascading negative effects on the economic sectors include road closures, lower revenue to the City based on reduced tourism and visitation, or excessive costs of firefighting and relocating people or natural and manmade resources (thus indirectly impacting City revenues). Transportation lifelines being closed and/or damaged could impede most of the population’s ability to commute to nearby cities, such as Carson City, Gardnerville, Placerville, and Sacramento. During the Caldor Fire, residents and visitors in the City were evacuated for 3 to 4 weeks from August to September. As a result of the month-long evacuation order, the City of South Lake Tahoe and counties of El Dorado and Douglas County in Nevada were impacted by economic loss, specifically loss revenue related to tourism and associated sales and tourist accommodation taxes.

Based on preliminary impacts on estimated losses on the economies in El Dorado County and Douglas County, Nevada provided by the University of Nevada – Reno Department of Economics and University Center for Economic Development and the Tahoe Prosperity Center, the South Shore Region’s revenue from the hotel and motel sector declined by approximately $21 million and the projected revenue loss for the retail and restaurant sector was $19.4 million (Tahoe Prosperity Center 2021). This resulted in $4.2 million in City tax losses and $1.7 million in City sales tax (Tahoe Prosperity Center 2021). Additional direct or indirect impacts to the economy could be further exacerbated by existing hazard issues such as earthquakes, drought, or severe weather, if those make it difficult to control wildfires or reestablish the economic drivers in the City’s Planning Area. These direct and indirect impacts were also evaluated by the Tahoe Prosperity Center following the Caldor Fire as they related to the secondary economic impacts accrued as those lost revenues are not re-spent throughout the rest of the economy. Based on the lost hotel/motel and retail and restaurant sector revenue losses, El Dorado County had an estimated employment loss of 522 employees, total labor income loss of $18.2 million, lost total value added of $29.2 million, and lost total economic activity of $50.3 million (Tahoe Prosperity Center 2021).

Critical Facilities and Infrastructure
Critical facilities are those community components that are most needed to withstand the impacts of a disaster, such as wildfire. Figure 4-43 shows critical facilities located in the City relative to the CALFIRE wildfire threat zones, while Table 4-44 summarizes the critical facilities according to their FEMA Community Lifeline designation and zones within the City Planning Area and broken down by the critical facilities within the City limits, SOI, and outside the City’s Planning Area. An overlay analysis using GIS was performed to determine where critical facilities are located within CALFIRE Fire Threat Zones ranked low, moderate, or high. Several critical facilities are also within non-fuel zones. Based on these results, a total of 34 critical facilities within the City limits are found in high fire threat zones, 19 critical facilities within the SOI are in high fire threat zones, and 11 critical facilities outside the City’s Planning Area are within high fire threat zones (Table 4-44). Sensitive critical facilities, such as potable water pump stations and water storage facilities are not shown on Figure 4-44.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-153 Table 4-44 FEMA Community Lifelines and Facility Types Relative to Wildfire Threat Zones Location FEMA Community
Lifeline Category
Fire Threat Level
High Moderate Low Non-Fuel Total
Within the City
Boundary
Communications 2 0 0 10 12
Energy 0 0 0 2 2
Food, Water, Shelter 24 2 2 19 47
Hazardous Material 0 0 0 2 2
Health and Medical 1 0 0 5 6
Safety and Security 7 0 4 29 40
Transportation 0 0 1 10 11
SUBTOTAL 34 2 7 77 120
Sphere of
Influence
Communications 0 1 0 0 1
Energy 0 0 0 0 0
Food, Water, Shelter 14 9 3 7 33
Hazardous Material 0 0 0 0 0
Health and Medical 0 0 0 0 0
Safety and Security 1 0 0 7 8
Transportation 4 0 0 3 8
SUBTOTAL 19 11 3 17 50
Outside
Planning Area
Communications 0 0 0 0 0
Energy 0 0 0 0 0
Food, Water, Shelter 11 5 1 5 22
Hazardous Material 0 0 0 0 0
Health and Medical 0 0 0 1 1
Safety and Security 0 0 1 1 2
Transportation 0 0 0 0 0
SUBTOTAL 11 5 2 7 25
TOTAL 64 18 12 101 195
Source: El Dorado County 2021; HIFLD, CALFIRE 2017 Forest and Rangeland Assessment (FTHRT14_2), Wood Analysis 2021 According to California’s Fourth Climate Assessment, wildfire may be the biggest immediate threat to California’s transportation system, as vegetation fuel accumulation continues to increase (California Natural Resources Agency 2018). Wildfires can also lead to mudslides and debris flows, later resulting in the temporary transportation system closures or other key impacts to the community. Studies cited in the most recent climate assessments for the Tahoe Basin found that a considerable amount of infrastructure is exposed to wildfire risk, with the highest risk being roads and highways and major electrical and water utilities. Transportation or freight activity may be disrupted, while smoke and firefighting operations can lead to temporary service disruptions that can additionally affect movement of goods and services (California Natural Resources Agency 2018).

Historic, Cultural, and Natural Resources
The City has seven cultural and historic resources, as summarized under Section 4.2 of this plan. Since these structures and historic districts are sensitive in nature and may not have been built according to the latest building codes due to their age, it is expected that they might be at risk of wildfires (e.g. because of 650
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-154 their potential inability to withstand significant heat). However, other areas such as parks or natural spaces along the Upper Truckee River and Trout Creek and large public lands within and adjacent to the City could also be at risk of a wildfire, but these places would need to be further studied to determine vulnerability and risk more specifically.

Future Development
Population growth and development in the City of South Lake Tahoe is steady and only recently increasing. The City is expected to grow by the year 2030 by approximately 2%, which the average annual growth rate (AAGR) for El Dorado County from 2000 to 2050. While growth is fairly limited in the Tahoe Basin, even small increase in urbanization of the Planning Area makes wildfire vulnerability a growing issue, as future development in the WUI will increase risk to this hazard city-wide. WUI related risks can however be managed with strong land use regulations and building code requirements. For example, development in the WUI can be limited, or where permitted can require firebreaks between development and forestland, as well as enforce that building construction be compliant with CBC Chapter 7A: Materials and Construction Methods for Exterior Wildfire Exposure. The City’s General Plan and Municipal Code can also be amended to address these land use regulations.

Risk Summary
Potential losses from wildfire within the City’s Planning Area include human life, structures and other improvements, natural and cultural resources, quality and quantity of water supplies, timber, and recreational opportunities. Economic losses could also result. Smoke and air pollution from wildfires can be a severe health hazard and affect local economy and resident’s quality of life. In addition, wildfires can create conditions for other hazards such as flooding, debris flows, mudslides, and erosion following rain events.

Wildfires in and surrounding the City Planning Area are likely to happen given the areas fire history, projected climate change influences, and residential and sizable visitor population (representing potential sources of wildfire ignitions). Residents and secondary homeowners have an opportunity to reduce wildfire risk to neighborhoods by hardening structures (Assembly Bill [AB] 38) and creating defensible space around structures (CALFIRE 2021), which includes appropriate landscaping and fuels reduction. Land managers, ski resorts, and emergency services also can play a role reducing risk through forest thinning and fuel reduction efforts within the WUI defense zone and/or through providing services such as chipping, defensible space inspections, tree marking, and clearing hazardous fuels from urban lots and open space. Key findings based on the wildfire risk assessment are highlighted below:
• The level of wildfire risk will likely increase in the future due to the effects of climate change, and as the City assesses and monitors the level of risk, they will adjust the emergency preparedness and hazard mitigation efforts accordingly.
• Wildfires are expected to have a probability of occasional occurrence in the future, given the local fuel, topography, and weather conditions and the extent of the WUI. Based on recent CAL FIRE future fire occurrence probability mapping, the City is mostly expected to have a high likelihood of fire from years 2026 to 2050.
• The areas of the City with high or very high fire threat, which in turn pose the highest risk to life and property, are located on the south of the Planning Area, along Highway 50 and Pioneer Trail. • There are 10,370 improved parcels within the City limits within the “very high” FHSZ that are vulnerable to wildfire (within LRA as defined by CAL FIRE). • The probability of future occurrence of wildfire is likely within the City’s Planning Area, the future occurrence outside the City is also likely and must account for areas where future occurrence of major 651
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• Seven historic and cultural properties and places are exposed to wildfire risks in the South Lake Tahoe Region based on the NRHP database.
• Population growth is expected to be approximately 2 percent by 2030 in the City, so WUI development may become a larger issue into the future. Building to the current code with regards to materials and structures is recommended based these development trends. • The overall risk significance of wildfire hazards to the City of South Lake Tahoe is High.

4.4 Human-Caused, Human-Health, and Climate-Related Hazard Profiles and Risk Assessment
The DMA does not require an assessment of human-caused and human-health hazards, but the City of South Lake Tahoe and HMPC decided to include human-caused hazards in this LHMP to several reasons.

First, the City wants to inform the public about all hazards, including both natural, human-caused, and human-health hazards. The City is also interested in the impact human-health and climate-related hazards could have on their community. The City also intends to take a proactive approach to disaster preparedness, and the HMPC feels that preparation for and response to a human-health disaster involves the same training and commitment of City resources as a natural hazard. The City is focused on reaching their 100% renewable energy goal among other climate adaptation goals related to carbon neutrality and community-wide deployment of solar, electrification opportunities, and transitioning to electric fleet vehicles. The following human-health hazard is discussed in this plan:
• Public Health Hazards: Epidemic/Pandemic
• Energy Shortages and Energy Resiliency
Other potential human-caused hazards, such as hazardous material incidents, cyber security, and terrorism threats were dismissed from further study. The City and HMPC noted that hazardous material incidents and releases are adequately covered by the planning mechanisms administered by El Dorado County’s Fire Protection District and the Hazardous Waste Division of the Department of Environmental Management.

4.4.1 Public Health Hazards: Epidemic/Pandemic
Hazard Description
A pandemic can be defined as a disease that attacks a large population across great geographic distances.

Pandemics are larger than epidemics in terms of geographic area and the number of people affected.

Epidemics tend to occur seasonally and affect much smaller areas. Pandemics, on the other hand, are most often caused by new subtypes of viruses or bacteria for which humans have little or no natural resistance. Consequently, pandemics typically result in more deaths, social disruption, and economic loss than epidemics.

Three conditions trigger a pandemic declaration:

1. A new virus subtype must emerge that has not previously circulated in humans (and therefore there is no pre-existing immunity),

2. This new subtype must be able to cause disease in humans, and

3. The virus must be easily transmissible from human-to-human. 652
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-156 Since March 2020, the City of South Lake Tahoe, the nation, and the world are dealing with the COVID-19 pandemic (caused by the SARS-CoV-2 virus), confirming that pandemic is a key public health hazard in the Planning Area. This hazard risk assessment includes an analysis of pandemic risk across the City and an analysis of the impacts of the hazards profiled in this plan on public health.

Unlike seasonal flu, a pandemic has much greater potential for loss of life and significant social disruption due to higher rates of transmission and more severe health impacts. The SARS-CoV-2 virus has a much higher rate of transmission than the seasonal flu, primarily by airborne transmission of droplets/bodily fluid. Common symptoms include fever, cough, fatigue, shortness of breath or breathing difficulties, and loss of smell and taste. While most people have mild symptoms, some people develop acute respiratory distress syndrome with roughly one in five requiring hospitalization in the United States and a fatality rate between 1 to 2 percent. Because the virus can be transmitted by asymptomatic people, and due to the presence of several variants of SARS-CoV-2, the Delta Variant, for example, containing the spread has been a significant challenge across the globe.

Location
Extensive – Pandemics occur not only on a county or state level but on a national and global scale. It is likely that most communities in the City would be affected, either directly or by secondary impacts. Some indirect consequences may be the diversion of resources that may be otherwise available.

El Dorado County has reported 16,597 cases and 139 deaths from COVID-19 as of October 5, 2021.

According to the El Dorado County Public Health COVID-19 dashboard, the Tahoe Region, which encompasses South Lake Tahoe, has the highest number of cases – approximately 3,514 cases and 11 deaths as of October 5, 2021, among all the regions in El Dorado County, This is likely because South Lake Tahoe is one of the only two cities in El Dorado County and the surrounding Tahoe Region and itself are tourism and recreation hotspots while COVID-19 is transmitted primarily from human-to-human contact.

Extent (Magnitude/Severity)
Limited – The magnitude of a public health emergency will range significantly depending on the transmissivity and mortality rate of the virus. For example, pandemic influenza is easily transmitted from person to person, however, advances in medical technologies have greatly reduced the number of deaths caused by influenza over time.

Today, a much larger percentage of the world’s population is clustered in cities, making them ideal breeding grounds for epidemics. Additionally, the explosive growth in air travel means the virus could spread around the globe within hours. Under such conditions, there may be very warning little time for counties, states, and countries to prepare. Most experts believe we will have just one to six months between the time that a dangerous new influenza strain is identified and the time that outbreaks begin to occur in the United States. Outbreaks are expected to occur simultaneously throughout much of the nation, preventing shifts in human and material resources that normally occur with other natural disasters.

These and many other aspects make pandemics unlike any other public health emergency or community disaster. Pandemics typically last for several months to 1-2 years and have even longer lasting effects on the economy and communities.

As described by the World Health Organization (WHO), the Pandemic Intervals Framework (PIF) is a sixphased approach to defining the progression of a pandemic. This framework is used to guide pandemic planning and provides recommendations for risk assessment, decision-making, and action. These intervals provide a common method to describe pandemic activities that can inform public health actions. The 653
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The six-phase approach was designed for the easy incorporation of recommendations into existing national and local preparedness and response plans. Phases 1 through 3 correlate with preparedness in the pre-pandemic interval, including capacity development and response planning activities, while Phases 4 through 6 signal the need for response and mitigation efforts during the pandemic interval. Phase 6 was reached in El Dorado County during the 2020 COVID outbreak.

Pre-Pandemic Interval
Phase 1 is the natural state in which influenza viruses circulate continuously among animals but do not affect humans.

Phase 2 involves cases of animal influenza that have circulated among domesticated or wild animals and have caused specific cases of infection among humans.

Phase 3 represents the mutation of the animal influenza virus in humans so that it can be transmitted to other humans under certain circumstances (usually very close contact between individuals). At this point, small clusters of infection have occurred.

Pandemic Interval
Phase 4 involves community-wide outbreaks as the virus continues to mutate and become more easily transmitted between people (for example, transmission through the air).

Phase 5 represents a human-to-human transmission of the virus in at least two countries.

Phase 6 is the pandemic phase, characterized by community-level influenza outbreaks.

Previous Occurrences
Since the early 1900s, six lethal pandemics have swept the globe:
• 1918-1919 Spanish Flu: The Spanish Flu was the most severe pandemic in recent history. The number of deaths was estimated to be 50-100 million worldwide and 675,000 in the United States. Its primary victims were mostly young, healthy adults. At one point, more than 10 percent of the American workforce was bedridden.
• 1957-1958 Asian Flu: The 1957 Asian Flu pandemic killed 1 to 2 million people worldwide, including about 70,000 people in the United States, mostly the elderly and chronically ill. Fortunately, the virus was quickly identified, and vaccine production began in May 1957. • 1968-1969 H3N2 Hong Kong Flu: The 1968 Hong Kong Flu pandemic killed 34,000 Americans.

Again, the elderly were more severely affected. This pandemic peaked during school holidays in December, limiting student-related infections, which may have kept the number of infections down.

Also, people infected by the Asian Flu ten years earlier may have gained some resistance to the new virus.
• 2003 SARS Outbreak: Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a coronavirus, called SARS-associated coronavirus (SARS-CoV). SARS was first reported in Asia in February 2003. Over the next few months, the illness spread to more than two dozen countries in North America, South America, Europe, and Asia before the SARS global outbreak of 2003 was contained. According to the WHO, a total of 8,098 people worldwide became sick with SARS during the 2003 outbreak. Of these, 774 died. In the United States, only eight people had laboratory evidence of SARS-CoV infection. All of these people had traveled to other parts of the world where SARS was 654
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COVID-19 vaccines are currently being administered and around 53.6% of El Dorado County populations (12 years or older) have been fully vaccinated. It will take time for the entire population to achieve herd immunity since a certain percentage of the entire population needs to be fully vaccinated. Additionally, due to the uncertainty in the transmission of several variants of the SARSCoV-2 virus, the pandemic is expected to continue through 2021 and even 2022.

Other public health hazards have also occurred in the region. California officials closed parts of South Lake Tahoe in August 2021 because a dead chipmunk had tested positive for bubonic plague (The New York Times 2021). A woman who was walking her dog contracted the plague in August 2021. She responded well to antibiotics and was released from the hospital, but it was California’s first case of the plague in five years. Bubonic plague is naturally occurring in many parts of California, including the Sierra Nevada, and can be transmitted through bites from infected fleas. The Tallac Historic Site, Kiva Beach picnic area, and the Taylor Creek Visitor Center were closed while wildlife officials sprayed an insecticide to kill fleas.

People can contract the plague by the bite from an infected flea, touching or holding an infected rodent or being around a pet infected with the plague. While rare, contracting the plague is not unheard of. On average, about seven people every year test positive for the disease, according to the Centers for Disease Control and Prevention (CDCP). Symptoms include sudden high fever, chills, headache, nausea and pain and swelling of lymph nodes that develop between two to seven days after exposure (KIRO 7 2020).

Although bubonic plague nowadays is extremely rare and can be treated and cured, it killed millions of Europeans during the middle ages. The prevention of bubonic plague does not include a vaccine but does involve reducing exposure to mice, rats, squirrels and other animals that may be infected (Cleveland Clinic n.d.).

Probability of Future Occurrences
Occasional – Even before the COVID-19 pandemic began, most public health experts considered another major pandemic to be inevitable. However, there is no definite way to predict when the next pandemic might occur. Some indicators will be present, but not every new virus turns into a pandemic. Based on the five pandemics that have affected the United States in roughly the last 100 years, a pandemic occurs on average roughly every 20 years.

Climate Change Considerations
Additional research is needed to determine the effects of climate change on the frequency and duration of epidemics and pandemics. Climate change may influence vector-borne disease transmission, although the direction of the effects (increased or decreased incidence) will be location- and disease-specific. Many 655
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Deforestation is the largest loss of habitat worldwide and this loss forces animals to migrate and potentially contact other animals and spread germs. Large livestock can also serve as a source for spillover infections from animals to people (Bernstein 2020). The intensity and extent of certain diseases are projected to increase. According to the WHO, there has been research development into the linkages between climate and infectious disease transmission that examine the associations between climate variability and infectious disease occurrence, early indicators of emerging infectious disease impacts of climate change and using predictive models to estimate the future burden of infectious disease under different climate change scenarios (WHO 2003). In summary, future risks associated with climate change are difficult to predict, but changes in infectious disease transmission patterns are likely consequences of climate change. Climate change can impact when and where pathogens appear, particularly related to temperature and rainfall patterns.

Ongoing efforts to reduce GHG emissions, building climate resiliency, and creating robust public health campaigns to prevent or prepare for possible increased vector-borne diseases may help to reduce the impacts of climate change on pandemics.

Vulnerability Assessment
Preparing for, responding to, and recovering from a pandemic requires a strategy that includes a holistic suite of public health activities designed to lessen the impact on morbidity and mortality. These activities include education, vaccination, prophylaxis, isolation/quarantine, a robust contact tracing program, and the closure of public facilities. In addition, clear, concise communication with the public and with other agencies remains a critical component, as does the ability of the involved agencies to achieve collaboration and coordination. By their very nature, most pandemics, once started, will not be stopped until they have run their course. This course can be shortened and weakened by many factors, with vaccination being the most effective method for protecting the population. Pandemic plans describe strategies of preparedness, response, and recovery to attempt to decrease illnesses and deaths during the pandemic period to manageable levels (i.e., that do not overwhelm the critical infrastructures of the State) and to promote community resiliency and rapid recovery.

General Property
For the most part, property itself is not generally impacted by a human disease, epidemics, or pandemics.

However, as concerns about contamination increase, property may be quarantined or destroyed as a precaution against spreading illness. Additionally, traditional sheltering facilities including homeless shelters or temporary facilities set up to support displaced persons due to an evacuation or other reason due to a simultaneous disaster occurring cannot be done in a congregate setting. This requires additional planning considerations or the use of facilities that allow for non-congregate shelter settings, which may require approval of a request to FEMA for non-congregate sheltering, and may have an increased cost (such as the use of individual hotel rooms) as opposed to traditional congregate sheltering facilities.

People
Pandemics can affect large segments of the population for long periods. The number of hospitalizations and deaths will depend on the virulence of the virus. Risk groups cannot be predicted with certainty; the elderly, people with underlying medical conditions, and young children are usually at higher risk due to their higher exposure rates from schools, but as discussed above this is not always true for all infectious agents. People without health coverage or access to good medical care are also likely to be more adversely affected. The mental health of the public could also be impacted depending on the length of the event and public health guidance on prevention.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-4-160 As previously described in the Past Events section above, the COVID-19 pandemic has resulted in over 704,000 deaths in the U.S. alone (139 deaths in El Dorado County). In addition to the direct impacts, the pandemic has completely disrupted life for many people. Most large gatherings have had to be canceled, and many schools during the onset of the pandemic were temporarily closed. Sheltering in place and social distancing have been highly encouraged and, in some places, mandated, leaving some individuals isolated for months.

Critical Facilities and Infrastructure
In the event of a pandemic, especially one with high transmission rates and mortality rates such as COVID19, community lifelines, such as healthcare facilities, like hospitals will be heavily affected and may be overwhelmed due to a limited number of beds, doctor and medical staff, laboratory testing capacity, and possible personal protective equipment (PPE) shortages. Indirect impacts can also result in these facilities being temporarily offline due to testing or other precautionary monitoring and downed systems. Further, outbreaks in small cities and counties may cause medical facilities to reach capacity very quickly. These situations have already happened during the COVID-19 pandemic. Other critical facilities and infrastructure are not directly affected by a pandemic but may have difficulty maintaining operations and maintenance activities due to a significantly decreased workforce. Schools may also be forced to close.

Economy
Pandemics can have extensive economic impacts, as evidenced by the COVID-19 pandemic and associated restrictions on social gatherings. Social distancing requirements have affected nearly every segment of the local and national economy, most notably the restaurant and hospitality industries.

Additionally, tourism and recreation industries may be impacted in affected areas. As a result, the unemployment rate can increase, which also occurred in 2020 due to the COVID-19 pandemic. Other economic impacts include varying disruptions in the food supply chains and essential medical services.

Historic, Cultural and Natural Resources
Impacts on these resources are typically minimal. However, reduced tourism during outbreaks could lead to additional economic impacts.

Future Development
Population growth and development contribute to pandemic exposure. Future development in and around the City has the potential to change how infectious diseases spread through the community and impact human health in both the short and long term. New development may increase the number of people and facilities exposed to public health hazards. Greater population concentrations (often found in special needs facilities, businesses, and school campuses) put more people at risk. During a disease outbreak, those in the immediate isolation area would have little to no warning, whereas the population further away in the dispersion path may have some time to prepare and mitigate against disease depending on the hazard, its transmission, and public notification.

Risk Summary
• Pandemics affecting the U.S. occur roughly once every 20 years but cannot be reliably predicted. • Effects on people will vary, but a significant portion of the population could become ill and may need to be hospitalized; casualties are also expected.
• Effects on property are typically minimal, although quarantines could result in short-term closures. 657
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• Lost productivity due to illness and potential business closures could potentially have severe economic impacts, such as increased unemployment rates in the City. Social distancing requirements and fear of public gatherings could also significantly reduce in-person commerce. • Ongoing mitigation activities should focus on disease prevention, especially during flu season. This includes, but is not limited to, pre-season community outreach campaigns to educate the public about risks and available support; establishing convenient vaccination centers; reaching out to vulnerable populations and caregivers; and issuing advisories and warnings. • The overall significance of pandemic/epidemic in the City of South Lake Tahoe is High.

4.4.2 Energy Shortages and Energy Resiliency
Hazard Description
Severe weather due to heavy snow and winter snowstorms across the City routinely lead to regional power outages, isolation of vulnerable neighborhoods, and white-out conditions on roadways. These power outages are often related to severe weather or increased power demands on the electrical grid due to a higher number of visitors and higher demands for heating. Deep snow, strong winds and severe cold create unsafe living conditions for vulnerable populations in the community during period of prolonged power outages. The events that result in power outages deprive the community of basic needs – the electricity that makes critical facilities and infrastructure, economic activity, and social independence and security possible. Resilient communities need resilient energy systems. The City recognizes these risks and supports education and outreach programs targeted at bringing awareness of the importance of increasing energy resiliency in South Lake Tahoe and reducing the risks of prolonged power outages related to severe weather.

High winds and potential wildfire threat also routinely lead to power outages in the Lake Tahoe Region, the Sierra Nevada, and across California. These power outages are a combination of new and intentional disruptions intended to protect communities from wildfire threat and an increase in unintentional disruptions associated with intermittent power shortages. While these outages may not result in the same isolation of vulnerable neighborhoods as heavy snow and winter snowstorms, they can severely impact populations dependent on electric power for life-saving medical equipment. Since 2000, California has experienced a significant increase in emergency conditions related to shortfalls in power reserves, severe winter weather, high winds, and wildfire risk that in many instances have resulted in both intentional and unintentional power outages.

Electrical power disruptions are grouped into two categories: intentional and unintentional. Intentional disruptions include planned disruptions, unscheduled, demand-side management, and load shedding.

Planned disruptions are scheduled based on maintenance and upgrade needs. Unscheduled disruptions are completed to address emergency conditions. Demand-side management disruptions are related to customer agreements with utility providers to reduce electrical demand during periods of peak system loads. Load shedding occurs when the power system is under extreme demand due to customer demand or failure of system operations and it is necessary to intentionally disrupt the service to prevent larger system failures. A new intentional disruption type of power shortage has occurred in California related to wildfires that started as a result of downed power lines or electrical equipment during the Camp Fire in 2018. Because of the severity of this catastrophic wildfire event, the California Public Utilities Commission (CPUC) directed the three largest energy utilities in California to prepare their customers for wildfire threats and related power outages during severe weather events. This emergency preparedness resulted 658
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In comparison, unintentional disruptions are outages that come with no advance notice. These types of disruptions can be the most problematic and can include system failures or malfunction, equipment overload, fallen trees, vandalism, severe weather (lightning, high winds, flooding), and wildfires that damage transmission lines. Recognizing the different types of intentional and unintentional outages is important so the City can plan and effectively handle the related hazard events.

Geographic Location
Extensive – Intentional and unintentional power disruptions related to energy shortages or severe weather can occur anywhere in the City. The City is within Liberty Utilities service area, which delivers electricity to customers in South Lake Tahoe, North Lake Tahoe, Truckee, the communities of Verdi and Floriston to the north of the Lake Tahoe, and the communities of Walker, Woodfords, and Markleeville to the south of the Lake Tahoe.

Extent (Magnitude/Severity)
The severity of an intentional or unintentional power outage depends on the time of the year when the outage occurs. During the winter months when heavy snow and winter snowstorms occur in the City, the impacts related to power outages can be greater compared to the summer months when power outages are intentional and planned events due to high winds and wildfire risk. Winter unintentional power outages happen with no advance notice, when road conditions are poor, outside temperatures are cold, and when the community has limited access to back-up power generation sources. PSPS events are scheduled more during summer and fall months (wildfire season) to prepare customers and communities for wildfire threat and potential intentional power outages.

The electrical transmission and distribution lines that may be considered for de-energization due to wildfire safety concerns and PSPS events are those that pass through areas that have been designated by the CPUC as at elevated (Tier 2) or extreme (Tier 3) risk for wildfire, as shown in Figure 4-44. The specific area within the Liberty Utility service area that these shutoff events will affect will depend on the forecasted dry and high wind weather conditions and what lines Liberty Utilities needs to turn off for public safety. For example, while a utility customer may not live or work in a high fire threat area, their power may be shutoff if their community relies upon a transmission or distribution line that passes through an area experiencing extreme fire threat conditions. This means a Liberty Utilities customer (or City resident) should be prepared for PSPS events, and the impacts on the community should be less severe.
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The HMPC noted there have been numerous winter
snowstorms and high wind events over the past 5 years
that have resulted in a combination of unintentional and intentional power disruptions. Liberty Utilities provides two online tools to track recent and current power
outages related to winter storms. They also have an
online tool for planned or intentional outages related to PSPS. The Winter Storm Outage Tracker maps and lists
winter storm outage incidents by date and time, area
impacted, number of customers impacted compared to
the total customers in the service area, and the
estimated restoration times.

For example, from December 22, 2021 through
December 26, 2021 there were multiple power outages
across Liberty Utilities service area in the Lake Tahoe Region due to a severe winter snowstorm. Additional
power outages occurred in 2022 that started on January
4, 2022 and lasted through January 5, 2022 in the Fallen Leaf Lake neighborhood (outside the City limits). These outages impacted approximately 221 customers out of
the 24,306 customers in the utility’s service area (0.9%). Service was restored for most customers within several hours of the incidents. Detailed and publicly available power outage data was not available from Liberty Utilities beyond these recent dates.

Probability of Future Occurrences
Highly Likely – Given that climatic factors will continue influencing severe weather patterns and climate within the City and based on historical data of known unintentional power disruptions due to heavy snow, severe winter snowstorms and high winds and PSPS events, it is highly likely that energy shortages will occur in the future.

Climate Change Considerations
Climate change is expected to result in more frequent and severe natural disasters associated with changes in temperature, precipitation patterns, and extreme weather events. These weather patterns put energy infrastructure at risk by impacting the efficiency and reliability of power plants and supply systems, substations, and the capacity of power transmission and distribution lines. Climate change can result in increased demand for cooling in the summer during high heat events in the City and most residents in the City lack air conditioning or other forms of cooling systems. Secondary impacts related to energy shortages also affect vulnerable populations, particularly those that rely on electrical power for life-saving medical equipment, such as respirators. Other vulnerable populations include the elderly and very young who are more sensitive to the loss of cooling systems that require electrical power. Power disruptions may also impact remote populations in and around the City, specifically communities that rely on groundwater wells that require electrical pumps for operation.

One of the most severe winter snowstorms occurred in
the Lake Tahoe region from December 23, 2021
through December 27, 2021. According to the UC
Berkeley Central Sierra Snow Lab the snowstorm
surpassed December 1970 as the snowiest December
storm ever recorded with over 202 inches. The record
was 238 inches in January 2017. During the storm,
most roadways in and out of the Tahoe Basin were
closed because of downed trees, narrow roads due to
limited snow removal on local streets, sleet and ice,
and traffic accidents. Above is a view from Ski Run
Boulevard looking north towards Lake Tahoe.

Photo Credit: Tahoe Daily Tribune 2021
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Property
Buildings should be resilient to planned and unplanned power disruptions. The temporary or prolonged loss of electrical power to residences, commercial buildings, and other facilities should be negligible, as the loss of power does not impact the structural integrity of the building. Instead, the loss of energy supply to a building limits the functionality of building operations.

People
The loss of electrical power in the City can impact people in many ways. Populations that loose power may be isolated in their homes without heat, refrigeration, lighting, or the ability to work from home if they lack internet connectivity. Power outages can be life-threatening to those dependent on electricity for life support. Vulnerable populations including the elderly, low-income and/or linguistically isolated populations can face worse isolation and exposure during energy shortage events and also face secondary effects of the hazards. Stranded commuters, travelers, or visitors to the City may also be vulnerable to cold temperatures and hypothermia. For example, during a recent severe snowstorm in the City, travelers were stranded on Highway 50 for several hours due to road closures, snow removal, and traffic accidents.

Critical Facilities and Infrastructure
All critical facilities, infrastructure, utility services and operations are vulnerable to energy shortages and power disruptions. The most common problems associated with power disruptions are the loss of utilities and public services, such as water, wastewater, transportation, food supply, public safety, and communications. During energy or power shortages traffic flow is disrupted because traffic lights and controls no longer operate. The availability of public safety services may be limited. Prolonged power outages can also have negative economic impacts on an entire region as commerce and good and services are delayed. Other secondary impacts may be the closure of government offices, schools, and other public facilities and service centers.

The resilience of power-dependent systems is only as strong as the energy systems upon which they depend. Hardening and modernizing energy infrastructure in the Lake Tahoe Basin is underway as our utility providers diversify the electrical power supply with renewable energy sources and make it more flexible through smart-grid technology, coupled with rapid restoration and continuity of services when disruptions occur. The City is already improving energy resiliency within the community through the commitment to transition to 100% municipal renewable energy by 2032 (or 100% decarbonization of the grid) and the ongoing investments in energy efficiency and support of renewable energy projects and infrastructure improvements.

Economy
Electrical energy shortages and interruption of power caused by winter storms, heavy snow and high winds, and wildfire risk can result in a range of cascading impacts on local businesses and the continuity of operations in the City. Businesses can no longer use cash registers or process payment transactions.

Gasoline pumps no longer operate, limiting accessibility for travelers and visitors. Restaurants may close because restaurant kitchen appliances and other equipment, such as lighting cannot work without power.

Hotels may also have limited accommodations due to lack of heating supplies, lighting, and other needs.

These impacts indirectly lead to economic losses in the commerce, tourism, and recreation industries in the City.
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The natural environment is not directly damaged by energy shortages or disruptions due to winter storms, high winds, or other severe weather hazards.

Future Development
Future development implies continued population growth, which increases the population exposed to the impacts of intentional and unintentional power disruptions and energy shortages. severe weather. Due to the frequency of severe winter storms, and heavy snow and high winds in the City, individual citizens, families, and businesses need to be prepared to address severe weather events when they occur. It is recommended that citizens, families, and businesses have a plan, store extra supplies of food and water, as well as other related, supplied supplies such as flashlights, batteries, firewood and have a battery-operated radio within their home or business. City residents should also limit travel during such events if they occur due to severe weather.

Risk Summary
• Severe weather due to heavy snow and winter snowstorms across the City routinely lead to regional power outages, isolation of vulnerable neighborhoods, and white-out conditions on roadways. High winds and potential wildfire threat also routinely lead to power outages in the Lake Tahoe Region, the Sierra Nevada, and across California.
• Electrical power disruptions are grouped into two categories: intentional and unintentional. • Intentional disruptions include planned disruptions, unscheduled, demand-side management, and load shedding. Unintentional disruptions are outages that come with no advance notice. • PSPS are safety procedures designed to protect customers and communities during the severe weather events when power is proactively shut off for public safety reasons in an effort to prevent a wildfire.
• The electrical transmission and distribution lines that may be considered for de-energization due to wildfire safety concerns and PSPS events are those that pass through areas that have been designated by the CPUC as at elevated (Tier 2) or extreme (Tier 3) risk for wildfire. • Winter power outages are common in the City. These hazard events have resulted in significant economic loss, traffic accidents, and injuries when combined with severe snow conditions. • Climate change is expected to result in more frequent and severe winter storms that could result in energy shortages in the City.
• Overall, the significance of energy shortages and need for energy resiliency is High. 663
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DMA Requirement §201.6(c)(3):
[The plan shall include the following:] A mitigation strategy that provides the jurisdiction’s blueprint for reducing the potential losses identified in the risk assessment, based on existing authorities, policies, programs, and resources, and its ability to expand on and improve these existing tools.

This section describes the process followed to develop the mitigation strategy and mitigation action plan for the City of South Lake Tahoe LHMP update. It describes how the City met the requirements for the FEMA 10-step planning process. This chapter specifically discusses:
• Planning Step 6: Set Goals
• Planning Step 7: Review Possible Activities
• Planning Step 8: Draft an Action Plan
The results of the planning process, the risk assessment, the goal setting, the identification of mitigation actions, and the participation of the HMPC led to the action plan documented in Section 5.2.3 Mitigation Action Plan. Taking all the above into consideration, the HMPC developed the following overall mitigation strategy:
• Communicate the hazard information collected and analyzed through this planning process so that the community better understands what can happen where and what they can do to be better prepared.
• Implement the action plan recommendations of this plan. • Use existing rules, regulations, policies, and procedures already in existence. - Given the flood hazards in the Planning Area, an emphasis will be placed on continued compliance with the NFIP and possible future participation in the CRS. • Monitor multi-objective management actions so that funding opportunities may be shared, projects may be packaged, and broader constituent support may be garnered among neighboring communities.

5.1 Goals and Objectives
DMA Requirement §201.6(c)(3)(i)
The hazard mitigation strategy shall include a] description of mitigation goals to reduce or avoid long‐term vulnerabilities to the identified hazards.

Up to this point in the planning process, the HMPC has organized resources, assessed hazards and risks, and documented mitigation capabilities. The resulting goals and mitigation actions were developed based on these tasks. The HMPC held a series of meetings and exercises designed to achieve a collaborative mitigation strategy as described further throughout this section.

During the initial goal setting meeting, the HMPC reviewed the results of the hazard identification, vulnerability assessment, and capability assessment. This analysis of the risk assessment identified areas where improvements could be made and provided the framework for the HMPC to formulate planning goals and objectives and the ultimate mitigation strategy for the City of South Lake Tahoe Planning Area. 664
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5.1.1 Goals Development Process
Goals were defined for the purpose of this mitigation plan as broad-based public policy statements that:
• Represent basic desires of the community;
• Encompass all aspects of community, public and private; • Are nonspecific, in that they refer to the quality (not the quantity) of the outcome; • Are future-oriented, in that they are achievable in the future; and • Are time-independent, in that they are not scheduled events.

Goals are stated without regard to implementation cost, schedule, and means. Goals are defined before considering how to accomplish them so that they are not dependent on the means or cost of achievement. The goal statements form the basis for objectives and actions that will be used as means to achieve the goals. Objectives define strategies to attain the goals and are more specific and measurable.

During the planning process, HMPC members were provided a list of the five existing goals from the 2008 HMP. The HMPC was also given a list of sample goals to consider from the California 2018 State Hazard Mitigation Plan (SHMP), City of South Lake Tahoe General Plan Health and Safety Element, and the 2018 El Dorado County LHMP. They were told that they could build upon the existing goals, combine, or revise the existing statements or develop new ones, keeping the risk assessment in mind. The HMPC participated in a virtual meeting and were asked to write or revise a goal statement and share it in the meeting chat room. Goal statements were reviewed and grouped into similar themes and discussed during the meeting. The goal statements from the HMPC were then reviewed during the second HMPC meeting until the team came to consensus. Based on the goal setting process, the HMPC identified the following five revised goals, which building upon the existing goal statements and provide direction for reducing future hazard-related losses within the City Planning Area:
• Goal 1 – Save lives and protect property and the safety of City residents, workers, and visitors. • Goal 2 – Reduce impact of future disaster events and the disruption of critical facilities and essential community services by building adaptive capacity to a changing climate. • Goal 3 – Enable and leverage post-disaster and Building Resilient Infrastructure Communities funding. • Goal 4 – Hasten timely recovery from disasters and build valuable partnerships. • Goal 5 – Demonstrate a dedication to improving the City’s safety and well-being and increasing public awareness of hazards and their mitigation.

Some of the new statements developed by the HMPC were determined to be better suited as hazardspecific objectives or actual mitigation actions. In summary, the revised goals focus on loss of life and property protection for all people in the City, reducing disaster impacts and disruptions to critical facilities by building capacity in the community to climate change, leveraging funding opportunities, accelerating timely recovery through collaboration and partnerships, and increasing public awareness.

5.1.2 Objectives Development Process
Next, the HMPC was asked whether they wanted to revise the existing objectives that summarized strategies to achieve each goal. In the existing 2008 HMP these objectives were linked to the hazards they mitigate. HMPC participants revised the objective statements during the third HMPC meeting based on initial input provided by the City and Wood staff. The revised objectives were also reviewed by the HMPC based on the City General Plan Health and Safety Element to look for opportunities to align the Health and Safety Element policies with the LHMP goals and objectives, and vice versa.

Based on the risk assessment review and goal setting process, the HMPC carried forward seven objective statements from the existing HMP and added two new objectives that focus on specific and measurable 665
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• Wildland Fire – Minimize the threat to lives and property posed by the possibility of wildland fire within the County through routine implementation of fuel reduction projects. • Earthquake – Minimize the threat to lives and property as a result of a possible earthquake within the Tahoe Basin Region by maintaining and upgrading critical facilities and infrastructure. • Severe Storm –Lessen storm-related damages for all types of severe storms that impact the City. • Flood – Minimize the threat to lives and property posed by the possibility of flood within the City. • Landslide – Reduce landslide events and overall soil erosion in the City. • Drought –Minimize the threat to property posed by the possibility of drought within the City by collaborating with water utilities and revisiting drought contingency actions. • Avalanche – Improve techniques of informing the public on the level of avalanche danger in the City's in order to diminish the threat to lives and property posed by the potential for avalanche. • Dam Failure – Improve dam inspection policy and procedures and identify new opportunities to minimize the threat to lives and property posed by the possibility of dam failure within the County. • Energy Shortages and Energy Resiliency – Create redundancies and promote resiliency in critical electrical infrastructure systems.
• Public Health Hazards – Develop public health and safety strategies to reduce risks on vulnerable populations.

5.1.3 Incorporation into Existing Planning Mechanisms
The information contained within this plan, including results from the vulnerability assessment, and the mitigation strategy will be used by the City to help inform updates and the development of local plans, programs and policies. The City Development Services Department should use this information when updating the General Plan Health and Safety Element after the current update to the Housing Element; this would ensure the Health and Safety Element complies with Assembly Bill (AB) 2140. The Building Division may use the hazard information when reviewing site plans on a case-by-case basis included in residential and commercial development applications, and the Public Works Department may utilize the hazard information when implementing the City’s CIP. Similarly, the City’s Sustainability Coordinator can integrate the information into future updates to the City’s 2020 CAP as it relates to climate adaptation strategies. The City should also incorporate information in this LHMP into future updates to the City’s park and recreation plans. Information may include hazard profile information on climate change impacts and the incorporation of climate change adaptation strategies into other local and regional plans and outreach programs. Lastly, the HMPC representatives reported on efforts to integrate the LHMP into local plans, programs and policies, such as the EOP and will report on these efforts at the annual HMPC plan review meeting.

5.2 Identification and Analysis of Mitigation Actions
DMA Requirement §201.6(c)(3)(ii)
The mitigation strategy shall include a] section that identifies and analyzes a comprehensive range of specific mitigation actions and projects being considered to reduce the effects of each hazard, with particular emphasis on new and existing buildings and infrastructure.

In order to identify and select mitigation actions to support the mitigation goals, each hazard identified in Section 4.1 Identifying Hazards: Natural Hazards was evaluated, as well as human-caused and human666 Chapter 5
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The natural hazards in order of priority level are:
• Wildfire
• Severe Weather: Heavy Snow/Winter Storms
• Flood
• Earthquake
• Drought
• Landslide and Debris Flows: Soil Hazards
• Severe Weather: Heavy Rain/Thunderstorms/Hail/Lighting/High Winds • Avalanche
• Dam Incidents
Public health hazards were identified by the HMPC as a priority hazard, as noted in Section 4.4 Humancaused and human-health hazards. Climate change impacts are qualitatively discussed in each hazard profile section. PSPS, commonly associated with severe weather events, are addressed by the Severe Weather: Winter Storms/Heavy Snow and Severe Weather: Heavy Rain/Thunderstorm/Hail/Lightening/High Winds actions as secondary impacts. However, given the severity of this hazard, energy shortage was a new climate-related hazard added to the LHMP update.

Once it was determined which hazards warranted the development of specific and new mitigation actions, the HMPC analyzed viable mitigation options that supported the revised goals and objectives. The HMPC was provided with the following list of categories of mitigation actions, which originate from the CRS:
• Prevention: Administrative or regulatory actions or processes that influence the way land and buildings are developed and built.
• Property protection: Actions that involve the modification of existing buildings or structures to protect them from a hazard or remove them from the hazard area. • Structural: Actions that involve the construction of structures to reduce the impact of a hazard. • Natural resource protection: Actions that, in addition to minimizing hazard losses, also preserve or restore the functions of natural systems.
• Emergency services: Actions that protect people and property during and immediately after a disaster or hazard event.
• Public information/education and awareness: Actions to inform and educate citizens, elected officials, and property owners about the hazards and potential ways to mitigate them.

At the mitigation strategy meeting the HMPC was also provided with a matrix showing examples of potential mitigation action alternatives for each of the above categories, for each of the identified hazards.

The HMPC was also provided a handout that explains the categories and provided further examples.

Another reference document titled “Mitigation Ideas” developed by FEMA in 2013, and FEMA’s 2020 “Mitigation Action Portfolio” were distributed to the HMPC via an online link. These documents list common mitigation activities by hazard and actions funded by FEMA. The HMPC was also instructed to consider both future and existing buildings in considering possible mitigation actions. This reference provides four categories of mitigation actions that were discussed at the HMPC meeting in addition to the NFIP/CRS categories. These include:
• Plans and Regulations
• Structure and Infrastructure Projects
• Education and Awareness
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Other alternatives discussed in the webinar include the four ‘A’s’ of mitigation:
• Alter the physical nature of the hazard
- Such as wildfire defensible space and fuels treatments, snow fences etc. • Avert the hazard away from people, buildings, and infrastructure - Can include engineered solutions, drainage, and channel improvements, floodproofing, fuel breaks
• Adapt to the hazard
- Through land use planning, building codes and design standards, warning systems etc. • Avoid the hazard
- Natural systems protection, open space, acquisition, or relocation of properties out of hazardous areas
As part of the review of mitigation options, long-term climate change adaptation strategies were also discussed. HMPC members were encouraged to incorporate climate change adaptation measures into the mitigation strategy of their respective agencies or organizations utilizing resources and guidance available on the Cal-Adapt website. These materials are included in Appendix B. HMPC members were encouraged to develop mitigation alternatives that would protect future, as well as existing, development from hazards per the DMA 2000 regulations. A facilitated discussion then took place to examine the existing actions in the 2008 HMP and analyze the other possible mitigation alternatives. With an understanding of the alternatives, a brainstorming session was conducted to generate a list of preferred mitigation actions.

The result was new and updated project ideas with the intent of meeting the identified goals and mitigating identified hazards.

Subsequent meetings with City department staff focused on refining and prioritizing new mitigation activities. During the subsequent meetings with the City, Wood reviewed the Draft LHMP update and remaining information or mitigation gaps that needed to be addressed. The City and Wood staff also discussed opportunities for plan integration and reviewed the plan implementation and maintenance procedures.

Prioritization Process
Once the mitigation actions were identified, the HMPC was provided with several decision-making tools, including FEMA’s recommended prioritization criteria, STAPLEE, to assist in deciding why one recommended action might be more important, more effective, or more likely to be implemented than another. STAPLEE stands for the following:
• Social: Does the measure treat people fairly? (e.g., social equity, different groups, different generations)
• Technical: Is the action technically feasible? Does it solve the problem? • Administrative: Are there adequate staffing, funding, and other capabilities to implement the project?
• Political: Who are the stakeholders? Will there be political and public support for the project? • Legal: Does the jurisdiction have the legal authority to implement the action? Is it legal? • Economic: Is the action cost-beneficial? Is there funding available? Will the action contribute to the local economy?
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The HMPC also discussed prioritizing actions that focus on climate adaptation, social equity, and community resiliency. They reviewed planning materials and tools designed to assist local communities in the development of climate adaptation and social equity goals and strategies.

In accordance with the DMA requirements (44 CFR, Section 201.6(c)(3)), an emphasis was placed on the importance of a benefit-cost analysis in determining action priority. As part of this evaluation, the benefits of proposed actions were weighed against estimated costs as part of the prioritization process. Other criteria used to assist in evaluating the benefit-cost of a mitigation action included:
• Does the action address priority hazards or areas with the highest risk? • Does the action protect lives?
• Does the action protect infrastructure, community assets or critical facilities? • Does the action meet multiple objectives?
• What will the action cost?
• What is the timing of available funding?
The mitigation categories, multi-hazard actions, and criteria are included in Appendix C: Mitigation Categories, Alternatives, and Selection Criteria.

Following the mitigation strategy meeting, once mitigation actions were compiled the HMPC used STAPLEE to determine which of the identified actions were most likely to be implemented and effective.

With these criteria in mind, team members prioritized the mitigation actions through an electronic polling exercise with the above criteria in mind, essentially voting on the projects. The electronic survey poll was completed based on additional mitigation action ideas and worksheets received after the third HMPC meeting. In summary, the projects with the most points became the higher priority projects. This process provided both consensus and priority for the recommendations.

The process of identification and analysis of mitigation alternatives allowed the HMPC to come to consensus and to collectively prioritize recommended mitigation actions. During the polling process, emphasis was placed on the importance of a benefit-cost review in determining project priority; however, this was not a quantitative analysis. Benefit-cost was considered in greater detail in the development of the Mitigation Action Plan detailed below in Section 5.2. For example, parameters were established for assigning subjective ratings (high, medium, low) to the benefits and costs of each mitigation action.

Specifically, each action developed for this plan contains a description of the problem and proposed project, the entity with primary responsibility for implementation, any other alternatives considered, a cost estimate, expected project benefits, potential funding sources, and a schedule for implementation.

Development of these project details for each action led to the determination of an overall high, medium, or low priority for each action.

Recognizing the limitations in prioritizing actions from multiple departments and the regulatory requirement to prioritize by benefit-cost to ensure cost-effectiveness, the HMPC decided to pursue mitigation action strategy development and implementation according to the nature and extent of damages, the level of protection and benefits each action provides, political support, project cost, available funding, and jurisdiction and department priority. This process guided the development of a prioritized action plan for the City of South Lake Tahoe. Cost-effectiveness will be considered in greater detail through a formal benefit-cost analysis when seeking FEMA mitigation grant eligibility and funding (e.g. HMGP, BRIC grant program) for eligible actions associated with this plan. 669
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5.2.1 Progress on 2008 Natural Hazards Mitigation Plan
The City of South Lake Tahoe has been implementing actions identified in the HMP developed by the City in 2008 and working steadily towards meeting the plan goals, objectives, and mitigation actions based on funding and staff availability. During the 2021-2022 LHMP update process the City reported on the status of all 29 of the 2008 HMP actions. The City provided input on whether the action had been completed, was deferred (not yet implemented, but still relevant for the updated plan), was in progress, or should be deleted. Table 5-1 summarizes the mitigation actions included in the 2008 HMP.

Table 5-1 Mitigation Action Progress Summary
Progress Category # Of Mitigation Actions
Completed 12
Deleted 7
Continue In Progress 8
Continue-Not Started 2
Total Continuing Actions 10
New Actions in 2021 19
Grand Total 29
Table 5-2 indicates the details for each of the 2008 mitigation action items that have been completed or deleted based on input from the HMPC.
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ID Corresponding
Hazard(s)
Mitigation Action Lead Agency Goals Priority Action Status Notes Completed
Action 1.1 Wildfire Review and update the City
ordinance to ensure the
construction of fire-resistant
homes in the future.

Fire Department, Public
Works Department,
Development Services
Department
Goals 1
and 2
High Complete. This action was completed with
the update of the City’s building code to
adherence to the CBC Chapter 7A standards,
which require new construction in the WUI to
use ignition-resistant building materials.

Action 1.3 Wildfire Utilize the existing urban wildland planning document to identify
WUI buffer areas surrounding
established communities in the
City.

Fire Department, USFS
Lake Tahoe Basin
Management Unit
(LTBMU), TRPA, Nevada
Fire Safe Council
Goals 2,
4, and 5
High Complete. The identification of WUI buffers
around communities in the City was reviewed
following the adoption of the 2008 HMP and
informed the LHMP update. Subsequent
planning guidance on construction in the
WUI was reviewed and current WUI spatial
datasets were incorporated in this LHMP
update to determine the number of City
parcels at risk and to visualize buffer areas
around communities in the City.

Action 2.1 Earthquake Review and update the City
Building Code to ensure the
construction of seismically-safe
buildings in the City of South Lake
Tahoe.

Development Services
Department
Goals 1,
2, and 5
High Complete. The City adopted in 2019 CBC that
includes the most recent and current seismic
regulations.

Action 3.1 Severe Storm Review and update City ordinance to facilitate adequate snow
storage and drainage easements.

TRPA, Public Works
Department, Development
Services Department
Goals 2,
4, and 5
High Complete. This action relates to requiring
adequate snow storage and drainage
easement on private property in the City and
has been completed.

Action 3.2 Severe Storm Dedicate snow storage and
drainage easements within all new
development.

TRPA, Public Works
Department, Building, and
Development Services
Department
Goals 2,
4, and 5
High Complete. New development in the City now
must dedicate snow storage areas and
drainage easement on-site plans.

Action 4.4 Flood Stockpile sandbags in order to
ensure an adequate supply to
combat erosion during flood
events.

Public Works Department Goals 1,
2, and 5
High Complete. Sandbag Station is set up behind
Fire Station #3 during winter.
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Mitigation Action Lead Agency Goals Priority Action Status Notes Action 5.2 Landslide Review and adapt the City grading
ordinance.

TRPA, Development
Services Department,
Public Works Department
Goals 1,
2, and 5
High Complete. City Public Works Department
confirmed that a Grading Ordinance was
adopted as part of Chapter 7.20 of the City’s
Code.

Action 5.3 Landslide Within the City grading ordinance, ensure cut and fill techniques
provide for finished slopes at the
angle of repose.

TRPA, Development
Services Department,
Public Works Department
Goals 1,
2, and 5
High Complete. City Public Works Department
confirmed that a Grading Ordinance was
adopted as part of Chapter 7.20 of the City’s
Code. Cut and fill is addressed in Section

7.20.510.

Action 5.4 Landslide Within the City grading ordinance, ensure that all disturbed slopes
are revegetated after grading to
reduce erosion potential while
promoting slope stabilization.

TRPA, Development
Services Department,
Public Works Department
Goals 1,
2, and 5
High Complete. City Public Works Department
confirmed that a Grading Ordinance was
adopted as part of Chapter 7.20 of the City’s
Code. Revegetation is addressed in Section

7.20.520.

Action 6.1 Drought Develop a homeowner's guide to
water conservation techniques.

STPUD Goals 1,
2, and 5
High Complete. STPUD has developed a range of
water conservation programs to help
homeowners conserve water when
restrictions are in place during droughts.

These include fixing water leaks, rebate
programs, and water wise landscape
consultations.

Action 8.1 Dam Failure Improve communication with the
California DWR to ensure that the
dams in the County have been
and continue to be inspected per
law.

County of El Dorado Goals 1,
2, and 5
Low Complete. The County completed DWR
communications and routine inspections by
DSOD.

Action 8.2 Dam Failure Develop a "Living with Dams"
pamphlet to inform potentially
affected citizens about dam safety
and being prepared in the event
of a dam emergency.

County of El Dorado Goals 1,
2, and 5
Low Complete. Outreach materials were
completed and distributed by the County.

Deleted
Action 1.4 Wildfire Reduce fuel loading within
identified wildland interface buffer
areas.

Nevada Fire Safe Council,

CCC, TRPA
Goals 2
and 5
High Deleted. This is an old action. The City
replaced this with a new action that aims to
develop a comprehensive hazardous fuel
reduction program to improve forest health
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Mitigation Action Lead Agency Goals Priority Action Status Notes and reduce the risk of catastrophic wildfire.

The program will include two components: 1)
fuel reduction projects to lessen the natural
build-up of fuel in the forest properties within
and surrounding the City, and 2) continuation
of the City-wide Defensible Space Program
for private properties in the City.

Action 1.6 Wildfire Endorse "firewood sales" by the
Forest Service as a method of fuel
load reduction in the National
Forests of the City.

USFS LTBMU Goals 1,
2, and 5
Low Deleted. This is an old action. The City
replaced this with a new action that is specific
to the City's purview and the lands they
manage. The City applied for a Southern
Nevada Public Land Management Act
(SNMPLA) Grant to fund hazardous fuels
reduction work at the airport and near the
proposed recreation center. There is
discussion of firewood sales on City property
from these fuels reduction projects; however,
a contractor will be responsible for sale or
removal of firewood. This grant funding has
not been awarded.

Action 1.7 Flood Sponsor a community "refuse
pile" to promote the removal of
vegetive refuse material from
private parcels.

Public Works Department,
Local Chipper Programs
Goals 2
and 5
Deleted. The South Tahoe Refuse (STR)
accepts yard and green waste. There is no
chipper program in the City, but the STR
program is already in place and accepts
refuse, so this action can be deleted.

Action 4.2 Flood Review and update City ordinance
to ensure only appropriate
construction takes place in
recognized flood-prone areas in
the future.

TRPA, Development
Services Department
Goals 1,
2, 4,
and 5
Deleted. This will be replaced by the new
mitigation action related to the Floodplain
Ordinance Update.

Action 7.1 Avalanche Initiate an avalanche warning
information system to inform and
warn users of the current level of
avalanche danger.

Heavenly Mountain
Resort, Public Works
Department
Goals 1,
2, and 5
Low Deleted. Heavenly Mountain Resort is outside
City limits; the City would support Search and
Rescue response, if called. The actual
response is covered in memorandum of
understanding (MOU) with other agencies,
like the County and USFS.
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Mitigation Action Lead Agency Goals Priority Action Status Notes Action 7.2 Avalanche Work with the ski resorts of the
City on educating skiers on
avalanche hazards.

Heavenly Mountain
Resort, Public Works
Department
Goals 1,
2, and 5
Low Deleted. Heavenly Mountain Resort is outside
the City limits and the City has limited
authority on projects outside City limits.

Action 7.3 Avalanche Develop and expand a patrol to
enforce and fine out-of-bounds
violations to reduce avalanche
potential.

USFS LTBMU Goals 1,
2, and 5
Low Deleted. Heavenly Mountain Resort and the
LTBMU have authority on federal lands to
limit the number of skiers or snowboarders in
terrain that is not managed for avalanche
control.
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1.1 associated with updating the City ordinance to ensure the construction of fire-resistant homes, which was reflected in the enforcement of the CBC Chapter 7A. Code enforcement ensures new construction complies with recent amendments to the CBC that ensure ignition-resistant building materials are used in the exterior design and construction of buildings located within the WUI. Similarly, Action 2.1 associated with updating the City Building Code was completed, which ensures the construction of seismically-safe buildings. Action 1.3 related to the identification of WUI buffer areas around established communities in the City was reviewed and informed the update of this LHMP. Subsequent planning guidance on construction in the WUI was reviewed since the 2008 HMP and recent WUI spatial datasets were assessed in this LHMP update to determine the number of City parcels within the WUI and potential buffer areas around established communities in the City, such as Tahoe Keys, Bijou, Sierra Tract, and the Al Tahoe neighborhoods. The identification of WUI buffers outside the City limits, within the SOI boundary were also analyzed in the LHMP update risk assessment on wildfire hazards. As a result, this mitigation action is complete.

Action 3.1 and Action 3.2 for severe storm and heavy snow are both also completed, since keeping storefronts clear of snow is a new requirement for the City, which addresses severe storm’s impact on both existing and future development. Action 3.3 for flood is complete because a sandbag station was set up at a City fire station. For landslide hazards, the City’s Public Works Department confirmed that Actions

5.2 through 5.4 have been adopted as part of City Ordinance Chapter 7.20 – Grading Ordinance.

Therefore, these three actions are the completed. For drought, given that the homeowner’s guide to conservation techniques has been designed and distributed, Action 6.1 is completed. For dam incidents, El Dorado County collaborates with DWR and works with the DSOD on routine inspections. The County also completed and distributed dam safety related pamphlets. Therefore, Action 8.1 and 8.2 are completed.

Seven mitigations actions where the City has limited jurisdiction or authority to enforce land use authority were deleted. These include Action 1.4, which is replaced by a proposed comprehensive Forest Fuel Reduction and Defensible Space Program. Action 1.6 which relates to the endorsement of firewood sales to reduce fuel loading was also deleted. This action was originally proposed by the U.S. Forest Service and the LTBMU was primarily responsible for promoting these sales. Action 1.7 relates to promoting the removal of refuse material from private parcels was also deleted because the STR accepts yard and green waste and therefore is already fulfilling this action. Action 4.2 will be replaced by a new and slightly modified mitigation action that targets at floodplain ordinance update. Three actions related to avalanche hazards were also deleted. Action 7.1 proposed to initiate an avalanche warning information system to inform and warn users of the current level of avalanche danger. This action, however, would involve Heavenly Mountain Resort’s cooperation, whereas the Resort is outside City limits. Moreover, the actual search and rescue response is covered in MOU with other agencies, such as El Dorado County and USFS, while the City would only support the response. Action 7.2 involves working with Heavenly Mountain Resort on educating skiers on avalanche hazards. This action was deleted because Heavenly Mountain Resort is outside City limits and outside the purview of City authority., Action 7.3 entailed expanding ski patrol to enforce and fine recreation users that violated out-of-bound area adjacent to Heavenly Mountain Resort in order to reduce avalanche safety hazards. This action would need to be implemented by Heavenly Mountain Resort and the LTBMU in order to effectively limit the number of skiers or snowboarders that access out-of-bound terrain adjacent to the ski area that is not managed for avalanche control. As a result, the City has limited authority to enforce these regulations.

The remaining actions from the 2008 HMP will carry forward into the 2021-2022 LHMP given they involve annual implementation and continuing actions. For example, Action 4.3 involves inspecting bridges within the City to ensure they are structurally safe from failure during peak flow scenarios; these inspections are completed by Caltrans and this action is ongoing and will be included in the plan update.

For this 2021 – 2022 LHMP update, new flood, drought, energy shortage, public health, and wildfire mitigation actions were developed. Ten of the 29 mitigation strategies from the 2008 HMP were carried 675
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5.2.2 Continued Compliance with National Flood Insurance Program (NFIP) Recognizing the importance of the NFIP in mitigating flood losses, an emphasis will be placed on continued compliance with the NFIP by the City of South Lake Tahoe. As a NFIP participant, South Lake Tahoe will continue to make every effort to remain in good standing with NFIP. This includes continuing to comply with the NFIP’s standards for updating and adopting floodplain maps and maintaining and updating the floodplain regulations. The City also proposes to update their Floodplain Ordinance to address areas for improvement based on a recent audit. Other details related to NFIP participation are discussed in the flood vulnerability discussion in Chapter 4 and in the capability assessment in Chapter 2.

Additional actions are related to possible future participation with the CRS program.

5.2.3 Mitigation Action Plan
Requirement §201.6(c)(3)(iii)
The hazard mitigation strategy shall include an] action plan, describing how the action identified in paragraph (c)(3)(ii) of this section will be prioritized, implemented, and administered by the local jurisdiction. Prioritization shall include a special emphasis on the extent to which benefits are maximized according to a cost benefit review of the proposed projects and their associated costs.

This action plan presents the recommendations developed by the HMPC outlining how the City can reduce the risk and vulnerability of people, property, infrastructure, and natural and cultural resources to future disaster losses. The mitigation actions developed by the HMPC are summarized in Table 5-3 and listed in detail in the mitigation action worksheets that follow. Table 5-3 is a summary table for quick reference. It identifies the mitigation action title, lead agency/department, hazards mitigated, priority and if the action mitigates losses to existing or future development. The ‘Related Goal’ column notes which of the five goals in Section 5.2 that the action helps achieve. The action worksheets that follow provide more background information, ideas for implementation, lead agency, partners, potential funding sources, cost estimates, benefits, and timeline for each identified action.

The City has other existing, detailed action descriptions in planning documents, such as General Plan Health and Safety Element, CIP, and other planning mechanisms. These actions are considered to be part of this plan, and the details, to avoid duplication, should be referenced in their original source document.

The HMPC also realizes that new needs, priorities, and adaptation strategies may arise as a result of a disaster or other circumstances and reserves the right to support new actions and strategies, as necessary, as long as they conform to the overall goals of this plan.

The actions included in this mitigation strategy are subject to further review and refinement; alternatives analyses; and reprioritization due to funding availability and/or other criteria. The City is not obligated by this document to implement any or all of these projects. Rather this mitigation strategy represents the desires of the City, the HMPC, and the community to mitigate the risks and vulnerabilities from identified hazards. Many of the action items included in this plan are also a collaborative effort among City staff, Conservancy, TRPA, STPUD, LVFPD, Tahoe Prosperity Center, El Dorado County, and other state, regional, and local agencies and stakeholders in the City’s Planning Area. 676
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Action
ID
Action Title New
Action/2008
Action
Hazard(s)
Mitigated
Responsible
Office / Agency
Cost Estimate and
Potential Funding
Priority Timeline Goals &
Lifelines
Dam Incidents
DI-1 Regularly coordinate with dam
owners and operators, specifically
the El Dorado Irrigation District and
the South Tahoe Public Utility
District on dam evaluations and
inspections, dam rehabilitation
activities, emergency action
planning and EAP updates, and
early warning and notification
messaging related to the
implementation of the City of
South Lake Tahoe EOP procedures.

New Action Dam
Incidents
Fire Department,
El Dorado
Irrigation District,
South Tahoe
Public Utility
District
<$10,000, General
Fund
Low 3-5 years Goals 1, 2,
3, 4 and 5
Drought
D-1 Incentivize drought-tolerant
landscaping that is also fireresistant
New Action Drought,
Wildfire
Public Works
Department
<$10,000, General
Fund
Medium 3-5 years Goals 1, 2,
and 5
Earthquake
E-1 Develop a homeowner's guide to
earthquake preparedness
techniques.
2008 Action Earthquake Fire Department,
Development
Services
Department
$10,000 – $100,000,
General Fund
Medium 1-3 years Goal 5
E-2 Inspect all City buildings and,
where applicable, upgrade
structures to withstand earthquake
events
2008 Action Earthquake Development
Services
Department,
Public Works
Facilities Division
$10,000 – $100,000,
Federal HMGP
Grants
Medium 3-5 years Goals 2
and 5
Energy Shortages
ES-1 South Tahoe Zero Energy District
(STZED) Connected Community
Partnership
New Action Energy
Shortages,
Severe
Weather:

Winter
Storms and
City Manager’s
Office
$3,000,000 -
$7,000,000
High 1-3 years Goals 1, 2,
3, 4, and 5
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ID
Action Title New
Action/2008
Action
Hazard(s)
Mitigated
Responsible
Office / Agency
Cost Estimate and
Potential Funding
Priority Timeline Goals &
Lifelines
Heavy
Snow,
Severe
Weather:

High Wind
Flood
F-1 Within new permit applications
applicable to existing parcels,
remove existing development from
recognized flood-prone areas or
require appropriate construction
and methods to minimize impacts
from flooding
2008 Action Flood Development
Services
Department
<$10,000, General
Fund
High 1-3 years Goals 1, 2,
4, and 5
F-2 Floodplain management ordinance
update
New Action Flood Development
Services
Department
$10,000 – $100,000,
General Fund
HMA HMGP Funds,
Floodplain
Management,
Protection, and Risk
Awareness Grant
Program
(Proposition 6)
Medium 1 year Goals 1, 2,
3, 4, and 5
F-3 Master storm drainage project New Action Flood Public Works Department
$100,000 –
$1,000,000, General
Fund, HMGP Grants
High 3-5 years Goals 1, 2,
3, 4, and 5
F-4 Maintenance of storm drainage
system
New Action Flood Public Works
Department
$10,000 –
$1,000,000, General
Fund
High 1-3 years Goals 1, 2,
3, 4, and 5
F-5 Inspect all bridges within the City
to ensure they are structurally safe
from failure during peak flow
scenario
2008 Action Flood Public Works
Department,
Caltrans
$10,000 –
$1,000,000, General
Fund
Medium 3-5 years Goals 1, 2,
4, and 5
Landslide and Debris Flows: Soil Hazards
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ID
Action Title New
Action/2008
Action
Hazard(s)
Mitigated
Responsible
Office / Agency
Cost Estimate and
Potential Funding
Priority Timeline Goals &
Lifelines
L-1 Inspect road cuts and fills for signs
of failure and erosion and stabilize
slopes
2008 Action Landslide Public Works
Department,
Caltrans
$10,000 – $100,000,
General Fund,
HMGP Grants
High 3-5 years Goals 1, 2,
and 5
L-2 Within City zoning ordinance,
review and adapt measures that
limit construction on steep slopes
where extensive cut and fill would
be necessary
2008 Action Landslide TRPA,
Development
Services
Department
$50,000, General
Fund
High 3-5 years Goals 1, 2,
4, and 5
Severe Weather: Heavy Rain/Thunderstorms/Hail/Lightning/High Winds/Heavy Snow and Winter Storms SW-1 Continue to coordinate with El
Dorado County and Caltrans to
conduct snow removal and
maintain roadway operations to
promote winter public safety
New Action Severe
Weather:

Heavy
Snow and
Winter
Storms
Public Works
Department
$10,000 – $100,000,
General Fund
High 1-3 years Goals 1, 2,
4, 5
SW-2 Designate accessible public
warming shelters during severe
storm and flood events that result
in power outages and ensure the
shelters have adequate capacity;
heat, food, and water supplies; and
on-site permanent back-up power
generation that can serve
vulnerable populations, residents,
and visitors
New Action Severe
Weather:

Heavy
Snow and
Winter
Storms;
Energy
Shortages
City Manager’s
Office
$10,000 – $100,000,
General Fund
High 1-3 years Goals 1, 2,
4, 5
SW-3 Develop a Winter Response Plan
for vulnerable populations in the
City
New Action Severe
Weather:

Heavy
Snow and
Winter
Storms;
Energy
Shortages
Fire Department $10,000 – $100,000,
General Fund
High 1-3 years Goals 1, 2,
4, 5
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-5-17 Action
ID
Action Title New
Action/2008
Action
Hazard(s)
Mitigated
Responsible
Office / Agency
Cost Estimate and
Potential Funding
Priority Timeline Goals &
Lifelines
SW-4 Build community awareness about
severe winter snow storm
preparedness
New Action Severe
Weather:

Heavy
Snow and
Winter
Storms;
Energy
Shortages
Fire Department <$10,000, General
Fund
High 1-3 years Goals 1, 2,
4, 5
Wildfire
W-1 Enforce City ordinance relating to
road construction to facilitate
emergency vehicle ingress and
egress
2008 Action Wildfire Fire Department <$10,000, General
Fund
High 1-3 years Goals 2, 4,
and 5
W-2 Forest Fuel Reduction and
Defensible Space Program
New Action Wildfire Fire Department $100,000 –
$1,000,000, HMGP
Funds
High 1-3 years Goals 1, 2,
and 5
W-3 Promote forest health within the
National Forests and State lands of
the City to reduce fuel loading
2008 Action Wildfire Fire Department $500,000, HMGP
Funds
High 1-3 years Goals 1, 2,
and 5
W-4 Hazardous fuel treatment and
reduction at Airport and Recreation
Center
New Action Wildfire Fire Department $100,000 –
$1,000,000,
Southern Nevada
Public Land
Management Act
(SNPLMA) Grant
High 3-5 years Goals 1, 2,

3. 4 and 5
W-5 Develop a homeowner guide for
reducing the threat of wildland fire
to private homes
2008 Action Wildfire Fire Department <$10,000, HMGP
Funds
High 1-3 years Goals 1, 2,
4 and 5
W-6 Develop partnerships with
concerned citizen groups to
identify and implement
neighborhood-specific fire safety
programs
2008
Action/New
Action
Wildfire Fire Department $50,000, General
Fund
High 1-3 years Goals 1, 2,
4, and 5
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-5-18 Action
ID
Action Title New
Action/2008
Action
Hazard(s)
Mitigated
Responsible
Office / Agency
Cost Estimate and
Potential Funding
Priority Timeline Goals &
Lifelines
W-7 Fire hazard defense – Home
Hardening Program
New Action Wildfire Development
Services
Department
$100,000 –
$1,000,000, HMGP
Funds
High 1-3 years Goals 1, 2,
3, 4, and 5
W-8 Enhance reliability and availability
of water distribution system for fire
flow and ensure appropriate water
pressure
New Action Wildfire Fire Department $10,000 –
$1,000,000, HMGP
Funds
High 1-3 years Goals 1, 2,

3. 4 and 5
W-9 Routine updates to City Evacuation
Plan including the development of
procedures that identify and
address the needs of socially
vulnerable populations in the City
New Action Wildfire City Manager’s
Office
$50,000, General
Fund
High 1-3 years Goals 1, 2,

3. 4 and 5
Public Health Hazards: Epidemics/Pandemics
PH-1 Pandemic Response Plan New Action Public
Health
Hazards
City Manager’s
Office
$10,000 – $100,000,
General Fund
High 1-3 years Goals 1, 2,
3, 4, and 5
Multi-Hazard
MH-1 Reverse 911 System New Action MultiHazardPolice
Department
$10,000 – $100,000,
General Fund
High 1-3 years Goals 1, 2,
3, and 5
MH-2 Routine LHMP Update New Action MultiHazardFire Department $10,000 – $100,000, HMGP Funds
High 3-5 years Goal 1, 2,
3, 4 and 5
MH-3 Local EOP Review New Action MultiHazardFire Department $10,000 – $100,000, General Fund
High 1-3 years Goal 1, 2,
3, 4 and 5
MH-4 Disaster Preparedness Plan New Action MultiHazardFire Department $10,000 – $100,000, General Fund
High 1-3 years Goal 1, 2,
3, 4 and 5
MH-5 Examine Retrofitting Utilities to
Below Ground Level and Analyzing
Options with Local Utility Providers
New Action MultiHazard,
Severe
Weather,
Wildfire
City Manager’s
Office
$50,000, General
Fund
Medium 1-3 years Goal 1, 2,
and 4
The following mitigation actions provide project-specific information and implementation details on each mitigation activity identified. They are grouped by the type of hazard(s) they address.
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page-5-19 682 Chapter 5
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-20 DI-1 Regularly coordinate with dam owners and operators, specifically the El Dorado Irrigation District and the South Tahoe Public Utility District on dam evaluations and inspections, dam rehabilitation activities, emergency action planning and EAP updates, and early warning and notification messaging related to the implementation of the City of South Lake Tahoe EOP procedures.

Mitigation Project Title Regularly coordinate with dam owners and operators, specifically the El Dorado Irrigation District and the South Tahoe Public Utility District on dam evaluations and inspections, dam rehabilitation activities, emergency action planning and EAP updates, and early warning and notification messaging related to the implementation of the City of South Lake Tahoe EOP procedures.

Project Description,
Issue/Background
It is critical for dam owners and operators to coordinate EAP information with the local emergency management agencies that are responsible for developing and regularly updating their EOPs. EAPs are dam specific and contain suggested procedures for protecting the dam and protocols for issuing early warning and notification messages to emergency management authorities, like the City of South Lake, so they can carry out EOP procedures. These emergency planning and warning protocols are in place to minimize the impacts related to dam incidents. This mitigation action will ensure regular communication among the dam operating agencies, which will help the City understand current dam safety conditions and inspection reports, and how best to update the City’s EOP.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Dam Incidents
Goals(s) Addressed Goals 1, 2, 3, 4, and 5
Priority (High, Medium,
Low)
Low
Responsible Office/
Agency
Public Works Department, South Tahoe Public Utility District, El Dorado Irrigation District
Partners TRPA, Caltrans, County of El Dorado
Potential Funding General Fund, HMGP Grants
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action will help mitigate dam incident hazards
Timeline 3-5 years
683
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-21 D-1 Incentivize drought-tolerant and fire-resistant landscaping.

Mitigation Project Title Incentivize drought-tolerant and fire-resistant landscaping.

Project Description,
Issue/Background
Drought-tolerant landscaping and the selection of fire-resistant plants has various benefits. It can reduce water use and lower water bills.

Drought-tolerant plants can be attractive plants but require less maintenance. These plants also tend to develop deeper roots that help stabilize slopes and soil. They can also help with groundwater recharge.

This action involves continued collaboration with the STPUD and other water utilities in the City limits to incentivize drought-tolerant and fireresistant landscaping to better prepare communities and the City when facing impact and threat from drought and wildfire hazards. The City can support the action by providing resources to property owners in coordination with STPUD based on their existing educational resources on water conservation, irrigation efficiency, and landscaping consultations (https://stpud.us/waterconsv/).

As part of this action, the City will also consider developing requirements that mandate fire-resistant landscaping as part of site plan review and approval. This would involve amending Section 5-24 (Landscaping) of Title 5 Development Standards of the City Code to require landscape plans for all new and rehabilitated developments to conform to the principles of fire-safe landscaping.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Drought, Wildfire
Goals(s) Addressed Goals 1, 2, and 5
Priority (High, Medium,
Low)
Medium
Responsible Office/
Agency
Public Works Department
Partners STPUD, Tahoe Keys Water Company (TKWC), Lukins Brothers Water Company, Lakeside Park Mutual Water Company
Potential Funding General Fund
Cost Estimate <$10,000
Benefits (Avoided
Losses)
Drought-tolerant landscaping can lower water-related expenses and save water resources; landscaping that is both drought-tolerant and fireresistant can mitigate the impact of wildfire and drought hazards and reduce potential losses caused by drought and wildfire hazards.

Timeline 3-5 years
684
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-22 E-1 Develop a homeowner's guide to earthquake preparedness techniques
Mitigation Project Title Develop a homeowner's guide to earthquake preparedness techniques Project Description,
Issue/Background
The City will develop a homeowner’s guide that educates and encourages property owners in the City to remain safe during and after earthquake events. The guide will summarize non-structural retrofits homeowners can implement to protect appliances and furniture in their home, such as large free-standing cabinets, appliances, and water heaters. The guide may also summarize structural retrofits homeowners can implement to protect their home, such as foundation and floor improvements and wood-framed wall and garage upgrades.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Earthquake
Goals(s) Addressed Goal 5
Priority (High, Medium,
Low)
Medium
Responsible Office/
Agency
Fire Department, Development Services Department
Partners County of El Dorado, CAL FIRE
Potential Funding General Fund
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
A homeowner's guide to earthquake preparedness techniques can educate homeowners on earthquake preparedness.

Timeline 1-3 years
685
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-23 E-2 Inspect all City buildings and, where applicable, upgrade structures to withstand earthquake events.

Mitigation Project Title Inspect all City buildings and, where applicable, upgrade structures to withstand earthquake events.

Project Description,
Issue/Background
The City will conduct a comprehensive survey of the structural conditions of all public-owned buildings and critical facilities owned by the City. This will include the identification of soft-story structures, if present. Once the inspection survey is completed, the City will upgrade, retrofit, or replace structures, as needed. These upgrades will better prepare the City to withstand future earthquake events and any risk of collapse or damage.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Earthquake
Goals(s) Addressed Goals 2 and 5
Priority (High, Medium,
Low)
Medium
Responsible Office/
Agency
Development Services Department, Public Works Facilities Division Partners County of El Dorado
Potential Funding General Fund, HMGP Grants
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
Upgrading structures to withstand earthquake events can reduce or even avoided property losses caused by potential earthquake hazards.

Timeline 3-5 years
686
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-24 ES-1 South Tahoe Zero Energy District (STZED) Connected Community Partnership
Mitigation Project Title South Tahoe Zero Energy District (STZED) Connected Community Partnership
Project Description,
Issue/Background
The STZED Connected Community Partnership involves securing infrastructure for energy generation and storage with public agencies and project partners to minimize the impacts from climate change and energy shortages and to offset costs related to power purchase agreements (PPA) with local utility providers. The STZED will share and coordinate resources, strategies, technologies, and expertise with a goal to achieve zero net energy and zero carbon, where possible, for existing and new buildings within a combined energy generation portfolio. The STZED will partner with industry energy providers for utilization of PPA financing models for efficiency, electrification, load flexibility, energy management, and renewable implementation.

The STZED involves optimizing building and zero energy cluster-level energy/load management systems, including integration and coordination with participating jurisdictions and project partners. The STZED will be implemented by building upon an existing pilot project at the City of South Lake Tahoe’s Public Works campus. The STZED will also involve enhancing the energy efficiency of demonstration projects planned for construction in 2022 through 2024. The City of South Lake Tahoe Recreation and Aquatics Center and Sugar Pine Village are both anticipated to be designed and constructed as demonstration buildings within the STZED, with a goal of achieving zero energy while constructing energy-efficient buildings, generating on-site power, and encouraging active transportation.

The vision for the project is the development of a network of gridinteractive efficient buildings and strategically deployed distributed energy resources (DERs) that create a substation-level community clean energy system that aims to meet all energy needs of the STZED entities at all time periods, thereby reducing energy shortages and increasing the resilience of the South Lake Tahoe distribution grid. The partnership will be designed to be scaled and replicated as a model, particularly in similar high alpine and rural environments and will lay the foundation for all properties in the City of South Lake Tahoe to be powered by locallygenerated, renewable sources of energy, 24/7, in a community clean energy microgrid by 2030. This project is integrated with goals and projects noted in the City's Strategic Plan and 2020 CAP.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Energy Shortage, Energy, Communications
Goals(s) Addressed Goals 1, 2, 3, 4 and 5
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-25 Priority (High, Medium,
Low)
High
Responsible Office/
Agency
City Manager’s Office
Partners STPUD, LTUSD, Lake Tahoe Community College (LTCC), Barton Hospital, STR, Sugar Pine Village
Potential Funding General Fund, HMGP Grants, Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) Connected Communities Grant Funds
Cost Estimate $3,000,000 to $7,000,000
Benefits (Avoided
Losses)
This action can mitigate the impacts caused by climate change and energy shortages and offset costs related to external PPAs.

Timeline 1-3 years
688
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-26 F-1 Within new permit applications applicable to existing parcels, remove existing development from recognized flood-prone areas or require appropriate construction and methods to minimize impacts from flooding
Mitigation Project Title Within new permit applications applicable to existing parcels, remove existing development from recognized flood-prone areas or require appropriate construction and methods to minimize impacts from flooding.

Project Description,
Issue/Background
The City will work on promoting appropriate land uses on parcels located within recognized flood-prone areas. This will also be accomplished during site plan review on a case-by-case basis in accordance with enforcement of the City’s Floodplain Ordinance.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Flood
Goals(s) Addressed Goals 1, 2, 4, and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Development Services
Partners TRPA
Potential Funding General Funds
Cost Estimate <$10,000
Benefits (Avoided
Losses)
This will help mitigate flood hazard and reduce or even avoid property losses
Timeline 1-3 years
689
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-27 F-2 Floodplain management ordinance update
Mitigation Project Title Floodplain management ordinance update Project Description,
Issue/Background
The City’s Floodplain Management Ordinance is part of Chapter 6.65, Floodplain Management of the City’s Municipal Code under Title 6 Development Services. The current code specifies the NFIP requirements from Title 44, Code of Federal Regulations, Section 60.3 and adopts by reference the 2019 Edition of the California Building Standards Code, Title 24 of the California Code of Regulations in Chapter 6.15 Building Regulations.

This action involves a comprehensive update of the City’s Floodplain Management Ordinance by updating the regulations and referencing a higher BFE requirement in the 2019 California Building Standards Code.

Section 6.65.170 Standards of Construction currently references the minimum NFIP BFE. As part of the update, the City would amend Chapter

6.65, Floodplain Management to reflect the adopted 2019 CBC requirements. Ongoing collaboration with the TRPA would also promote higher floodplain management requirements for new development.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Flood
Goals(s) Addressed Goals 1, 2, 3, 4, and 5
Priority (High, Medium,
Low)
Medium
Responsible Office/
Agency
Development Services
Partners CA DWR, TRPA
Potential Funding HMA/HMGP Funds, Floodplain Management, Protection, and Risk Awareness Grant Program (Proposition 6 Funds)
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
Avoided property losses
Timeline 1 year
690
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-28 F-3 Master storm drainage project
Mitigation Project Title Master storm drainage project
Project Description,
Issue/Background
The City’s Stormwater Management Program aims to control and reduce the discharge of find sediment, nutrients, and other pollutants from private lands and City streets and facilities into Lake Tahoe. The Program accomplishes this goal through the Stormwater and Grading Ordinances.

The City also identified drainage problem areas and potential restoration projects in the 2008 Drainage Master Plan. Prioritized projects address flooding, property damage, and clarity of Lake Tahoe. Past projects included the Al Tahoe Erosion Control Project, Colorado Court Pump Station, Sierra Tract Erosion Control Projects, and Bijou Commercial Core Erosion Control Project. This action involves the identification of a new master storm drainage project that will upsize and upgrade the entire stormwater system in the City based on the existing inventory of culverts that need upgrades. While watershed-level restoration projects that reduce localized flooding are noted in the City’s current CIP and integrated into this LHMP update, City-wide upgrades to the existing stormwater system will protect critical facilities, reduce flooding and soil erosion, and minimize the impacts of climate change associated with increased precipitation, more frequent rain-on-snow events, and prolonged heavy rainfall and high peak flows that result in large volume runoff.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Flood
Goals(s) Addressed Goals 1, 2, 3, 4, and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Public Works Department
Partners TRPA, Caltrans, County of El Dorado
Potential Funding General Fund, HMGP Grants
Cost Estimate $100,000 – $1,000,000
Benefits (Avoided
Losses)
This action will help mitigate flood hazard and reduce or even avoid property losses
Timeline 3-5 years
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-29 F-4 Maintenance of storm drainage system
Mitigation Project Title Maintenance of storm drainage system Project Description,
Issue/Background
This action involves the regular maintenance and clearing of City storm drains of sediment and debris and ice and snow during winter months to prevent back-up and impacts to nearby infrastructure.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Flood
Goals(s) Addressed Goals 1, 2, 3, 4, and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Public Works Department
Partners Caltrans, County of El Dorado
Potential Funding General Fund
Cost Estimate $10,000 – $1,000,000
Benefits (Avoided
Losses)
This action will help mitigate flood hazard and reduce or avoid potential damage to the property and infrastructure.

Timeline 1-3 years
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-30 F-5 Inspect all bridges within the City to ensure they are structurally safe from failure during peak flow scenarios
Mitigation Project Title Inspect all bridges within the City to ensure they are structurally safe from failure during peak flow scenarios
Project Description,
Issue/Background
Caltrans inspects all bridges within the City including State Highway bridges, such as Lakeview boat ramp and Venice Drive bridge. Caltrans will notify the City in writing of any defects which require repair or mitigation. The City maintains two bridges: Lakeview Commons and Venice Drive.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Flood
Goals(s) Addressed Goals 1, 2, 4, and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Public Works Department
Partners Caltrans
Potential Funding General Fund
Cost Estimate $10,000 – $1,000,000
Benefits (Avoided
Losses)
This action will help mitigate flood hazard and reduce or avoid potential damage to the property and infrastructure.

Timeline 3-5 years
693
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-31 L-1 Inspect road cuts and fills for signs of erosion or failure and stabilize slopes
Mitigation Project Title Inspect road cuts and fills for signs of erosion or failure and stabilize slopes
Project Description,
Issue/Background
The City completed an extensive inspection of the City road system in 2021. As part of the inspection, areas were prioritized for improvements and slope stabilization. As part of routine road maintenance, the City Street Crews will continue to inspect road cuts and fills and retaining slopes and drainage maintenance infrastructure for signs of slope failure.

Ongoing inspections will allow the City to identify unstable slopes and areas for improvement. With the exception of the upper Heavenly area near the southern portion of the City, there are no other known landslide or soil erosion hazards.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Landslide
Goals(s) Addressed Goal 1, 2 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Public Works Department
Partners Caltrans
Potential Funding General Fund, HMGP Funds
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action will help mitigate landslide hazard and reduce or avoid potential danger from landslide hazard to property and infrastructure.

Timeline 3-5 years
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-32 L-2 Review and adapt measures that limit construction on steep slopes where extensive cut and fill would be necessary.

Mitigation Project Title Review and adapt measures that limit construction on steep slopes where extensive cut and fill would be necessary.

Project Description,
Issue/Background
Within City zoning ordinance, review and adapt measures that limit construction on steep slopes where extensive cut and fill would be necessary. This action is carried over from the 2008 HMP.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Landslide
Goals(s) Addressed Goal 1, 2, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Development Services Department
Partners TRPA
Potential Funding General Fund
Cost Estimate $50,000
Benefits (Avoided
Losses)
This action will help mitigate landslide hazard and reduce or even avoid potential danger from landslide hazard to property and infrastructure.

Timeline 3-5 years
695
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-33 SW-1 Continue to coordinate with El Dorado County and Caltrans to conduct snow removal and maintain roadway operations to promote winter public safety.

Mitigation Project Title Continue to coordinate with El Dorado County and Caltrans to conduct snow removal and maintain roadway operations to promote winter public safety
Project Description,
Issue/Background
This action involves ongoing coordination with the County of El Dorado and Caltrans on snow removal operations within and outside the City.

State Highway 50 is a four-lane highway that traverses the City of South Lake Tahoe. Snow removal along this major corridor is conducted by Caltrans. The City conducts snow removal of adjacent City roads and streets. Better coordination with the State and County will promote ongoing winter public safety.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Severe Weather: Heavy Snow and Winter Storm
Goals(s) Addressed Goal 1, 2, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Public Works Department
Partners County of El Dorado, Caltrans
Potential Funding General Fund
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action will help mitigate landslide hazard and reduce or even avoid potential danger from landslide hazard to property and infrastructure.

Timeline 1-3 years
696
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-34 SW-2 Designate accessible public warming shelters during severe storm events with adequate capacity; heat, food; and water supplies; and on-site permanent back-up power generation that can serve vulnerable populations, residents, and
visitors.

Mitigation Project Title Designate accessible public warming shelters during severe storm events with adequate capacity; heat, food, and water supplies; and on-site permanent back-up power generation that can serve vulnerable populations, residents, and visitors.

Project Description,
Issue/Background
The severe winter snow storms in the Lake Tahoe often result in frequent cold temperatures, heavy snow, and severe weather conditions. An accessible and public warming shelter will provide a safe place for people and visitors in the City to stay during the colder days and nights in the City. The designation and opening of shelters can be based on severe weather forecasts by the City’s Fire Department. The shelters can also be designated with input from the County of El Dorado OES. The program will serve the community, those experiencing homelessness, and those that live in homes that loose heat due to unintentional power outages.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Severe Weather: Winter Storms and Heavy Snow, Energy Shortages Goals(s) Addressed Goal 1, 2, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
City Manager’s Office
Partners Fire Department, El Dorado County
Potential Funding General Fund
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action will help mitigate the impacts on people, particularly sensitive and vulnerable populations that lack resources during severe winter weather.

Timeline 1-3 years
697
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-35 SW-3 Develop a Winter Response Plan for vulnerable populations in the City.

Mitigation Project Title Develop a Winter Response Plan for vulnerable populations in the City.

Project Description,
Issue/Background
This action addresses the needs of those most vulnerable to severe weather and energy shortages due to power outages. The action involves the development of a Winter Response Plan that minimizes impacts to populations most vulnerable to severe weather, energy shortages due to power outages, and wildfire impacts. The Winter Response Plan would focus on primary and secondary impacts associated with winter storms and heavy snow and loss of power. The Plan would address the needs of populations most vulnerable to severe winter weather in the City including individuals residing in senior homes or convalescent/nursing homes or younger children at child care facilities, schools, or other facilities. Vulnerable populations may consist of elderly, young, sensitive, or individuals with special medical needs that may need additional emergency response support during severe winter storms.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Severe Weather: Winter Storms and Heavy Snow, Energy Shortages Goals(s) Addressed Goal 1, 2, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners TRPA
Potential Funding General Fund
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action will reduce the impacts to sensitive and vulnerable populations in the City from severe winter weather.

Timeline 1-3 years
698
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-36 SW-4 Build community awareness about severe winter snow storm preparedness
Mitigation Project Title Build community awareness about severe winter snow storm preparedness.

Project Description,
Issue/Background
This action consists of creating a public awareness campaign focused on winter weather hazards. The purpose of the campaign is to build community awareness about severe winter snow storms, heavy snow, and extreme cold temperatures and how to avoid these hazards by staying indoors and traveling safety when there is ice and snow on the roads. The campaign can kick-off in early November around the same time as Winter Hazard Awareness Week and continue through the winter season.

Awareness informational resources may include tips and fact sheets about winter storms, outdoor winter safety, winter fire safety, and winter driving.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Severe Weather: Winter Storms and Heavy Snow, Energy Shortages Goals(s) Addressed Goal 1, 2, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners NWS
Potential Funding General Fund
Cost Estimate <$10,000
Benefits (Avoided
Losses)
This action will reduce the impacts to sensitive and vulnerable populations in the City from severe winter weather.

Timeline 1-3 years
699
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-37 W-1 Enforce City ordinance relating to road construction to facilitate emergency vehicle ingress and egress
Mitigation Project Title Enforce City ordinance relating to road construction to facilitate emergency vehicle ingress and egress.

Project Description,
Issue/Background
New construction in the City must contain adequate emergency vehicle ingress and egress. The City Fire Marshal conducts site plan review to ensure new development complies with code requirements related to ensuring emergency vehicles can safely enter, turn around, and exit commercial and industrial properties in the City.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire, Safety and Security
Goals(s) Addressed Goal 2, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners None identified.

Potential Funding General Fund
Cost Estimate <$10,000
Benefits (Avoided
Losses)
This action will help mitigate urban and wildfire hazards and minimize the time it takes the City to respond to an emergency.

Timeline 1-3 years
700
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City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-38 W-2 Forest Fuel Reduction and Defensible Space Program
Mitigation Project Title Forest Fuel Reduction and Defensible Space Program Project Description,
Issue/Background
The City shall develop a comprehensive hazardous fuel reduction program to improve forest health and reduce the risk of catastrophic wildfire. The program shall include two components: 1) fuel reduction projects to reduce the natural build-up of fuel in the forest properties within and surrounding the City, and 2) continuation of the City-wide Defensible Space Program for private properties in the City. The fuel reduction projects would occur on large City-owned properties. The City's Defensible Space Program is managed by the City’s Fire Inspector. The Defensible Space Program includes continuing routine inspections on lots in the City. This program would also include the production of educational materials to educate homeowners and property owners on ways to mitigate wildfire hazards. The City wants to enhance the program to mitigate potential wildfire threats more effectively in and near the City.

The City would add staff capacity to manage a seasonal crew of 25 individuals as part of a workforce development program earning a living wage. The seasonal crews would implement defensible space projects on public and private lands in the City.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire, Safety and Security
Goals(s) Addressed Goals 1, 2 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners Nevada Fire Safe Council, TRPA, California Conservation Corps, California Tahoe Conservancy
Potential Funding HMGP Funds
Cost Estimate $100,000 – $1,000,000
Benefits (Avoided
Losses)
This action will help mitigate wildfire hazard and reduce the potential danger from wildfire hazard to property, people and infrastructure.

Timeline 1-3 years
701
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-39 W-3 Promote forest health within the National Forests and State lands of the City by reducing fuel loading
Mitigation Project Title Promote forest health within the National Forests and State lands of the City by reducing fuel loading.

Project Description,
Issue/Background
The City will promote continued cooperation between the U.S. Forest Service LTBMU and California Tahoe Conservancy (Conservancy) on how to best continue fuels reduction and maintain the urban lot properties in the City. Fuels reduction work needs to be completed on these urban lots owned and managed by the LTBMU and Conservancy to reduce wildfire threat, minimize adjacent and neighborhood concerns, and promote safety.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire, Safety and Security
Goals(s) Addressed Goal 1, 2 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners USFS LTBMU, CTC
Potential Funding HMGP Funds
Cost Estimate $500,000
Benefits (Avoided
Losses)
This action will help mitigate wildfire hazard and reduce the potential danger from wildfire hazard to property, people and infrastructure.

Timeline 1-3 years
702
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-40 W-4 Hazardous fuel treatment and Reduction at Airport and Recreation Center
Mitigation Project Title Hazardous fuel treatment and reduction and Airport and Recreation Center
Project Description,
Issue/Background
The City submitted a grant application for funding associated with the Lake Restoration Act that will support the completion of hazardous fuel treatment projects on City-owned properties at the airport and recreation center. The City may allow firewood sales on these properties in coordination with the tree removal contractor. This action is related to a previous existing action that endorsed “firewood sales” on LTBMU property.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire
Goals(s) Addressed Goal 1, 2, 3, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners USFS LTBMU
Potential Funding Southern Nevada Public Land Management Act (SNPLMA) Grant Cost Estimate $100,000 – $1,000,000
Benefits (Avoided
Losses)
This action will help mitigate wildfire hazard and reduce the potential danger from wildfire hazard to property, people and infrastructure.

Timeline 3-5 years
703
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-41 W-5 Develop a homeowner guide for reducing the threat of wildland fire to private homes
Mitigation Project Title Develop a homeowner guide for reducing the threat of wildland fire to private homes
Project Description,
Issue/Background
Educational materials such as the homeowner guide were made available by the TFFT and the Tahoe Resource Conservation District (TRCD) in past hazard mitigation efforts. These outreach materials and the State requirements are evolving as wildfire risk across the region increases. As a result, the California Fire Safe Council, LVFPD, TFFT, and TRCD continually update and annually distribute new materials in the community. The homeowner guides and outreach materials acknowledge the City is a Fire Adapted Community and take responsibility for its wildfire risk by implementing actions to address safety, homes, neighborhoods, infrastructure, forests, and community assets. The homeowner guide will be complemented by neighborhood-scale efforts that prepare people and property for wildfires through defensible space awareness. It will promote the Tahoe Living with Fire website and encourage neighborhood leaders to prepare for wildfire through evacuation drills.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire
Goals(s) Addressed Goal 1, 2, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners TFFT, TRCD
Potential Funding HMGP Funds
Cost Estimate <$10,000
Benefits (Avoided
Losses)
This action will help mitigate wildfire hazard and reduce the potential danger from wildfire hazard to property, people and infrastructure by raising people’s awareness.

Timeline 1-3 years
704
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-42 W-6 Develop partnerships with concerned citizen groups to identify and implement neighborhood-specific fire safety programs
Mitigation Project Title Develop partnerships with concerned citizen groups to identify and implement neighborhood-specific fire safety programs
Project Description,
Issue/Background
The City continues to collaborate with the TFFT formed in 2008. The Fire Safe Communities, TFFT, and LVFPD partnership together implement various fire safety programs. This action was updated from the 2008 HMP to support the development of neighborhood groups and leaders that collaborate with program fire staff to protect communities from wildfire threat. Partnerships include educating neighborhoods, hosting block parties, and coordinating defensible space days. Two neighborhoods in the City have recently been designated Firewise Communities.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire
Goals(s) Addressed Goal 1, 2, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners TFFT, LVFPD, TRCD, California Fire Safe Council Potential Funding General Fund
Cost Estimate $50,000
Benefits (Avoided
Losses)
This action will help mitigate wildfire hazard and reduce the potential danger from wildfire hazard to property, people and infrastructure.

Timeline 1-3 years
705
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-43 W-7 Fire hazard defense - Home Hardening Program
Mitigation Project Title Fire hazard defense - Home Hardening Program Project Description,
Issue/Background
The Fire Hazard Defense Program will be a home hardening financial incentive program that will track state funding opportunities through the California Wildfire Home Hardening Program to provide financial incentives to homeowners for home hardening and defensible space upgrades to existing structures.

Financial assistance is anticipated to become available to Californians who take specific steps to ensure their property has the best chance of surviving a wildfire. The program will focus on hardening communities at extreme risk to wildfires, such as South Lake Tahoe and will prioritize those with high social vulnerability. It will provide direct financial assistance for low- and moderate- income households, in addition to education and outreach to entire communities. Fire science shows if more homes are “hardened,” communities are better protected from fire dangers. The program will take a whole community approach with the goal of hardening entire neighborhoods to increase their resilience to wildfires. The program will cover home retrofits with ignition-resistant materials, creating defensible space, and home modifications that include roof replacements, and upgrading to dual-paned windows and tempered glass. Information on home hardening can be found at:
www.readyforwildfire.org.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire
Goals(s) Addressed Goal 1, 2, 3, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Development Services Department
Partners
Potential Funding HMGP Funds
Cost Estimate $100,000 – $1,000,000
Benefits (Avoided
Losses)
This action will help mitigate wildfire hazard and reduce the potential danger from wildfire hazard to property, people and infrastructure.

Timeline 1-3 years
706
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-44 W-8 Enhance reliability and availability of water distribution system for fire flow and ensure appropriate water pressure Mitigation Project Title Enhance reliability and availability of water distribution system for fire flow and ensure appropriate water pressure
Project Description,
Issue/Background
Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire
Goals(s) Addressed Goal 1, 2, 3, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners
Potential Funding HMGP Funds
Cost Estimate $10,000 – $1,000,000
Benefits (Avoided
Losses)
This action will help mitigate wildfire hazard and reduce the potential danger from wildfire hazard to property, people and infrastructure.

Timeline 1-3 years
707
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-45 W-9 Routine updates to City Evacuation Plan including the development of procedures that identify and address the needs of socially vulnerable populations in the City
Mitigation Project Title Routine updates to City Evacuation Plan including the development of procedures that identify and address the needs of socially vulnerable populations in the City
Project Description,
Issue/Background
The City improved their emergency response capabilities by developing an interactive evacuation map and updated alert system in 2019. The 2018 wildfire season prompted public safety officials across California to reevaluate emergency response measures communities have in place for dealing with large-scale emergencies. These wildfires demonstrated the need to move from neighborhood-scale evacuations to regional evacuations. This action involves continuing to reevaluate, update, and implement the City’s Evacuation Plan. This action also involves identifying the socially vulnerable populations in the City, including seniors, children, persons with access and functional needs (AFN), medically-dependent, non-English speaking residents and workers, those experiencing homelessness, and those that are geographically isolated. Once socially vulnerable communities are identified, this action involves collaborating with these groups to identify and plan for their needs during an evacuation. This action can be integrated into the next EOP update.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Wildfire
Goals(s) Addressed Goal 1, 2, 3, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
City Manager’s Office
Partners Fire Department, Development Services Department, Family Centers, Food Banks, Tahoe Coalition for the Homeless
Potential Funding General Fund
Cost Estimate $50,000
Benefits (Avoided
Losses)
This action will help mitigate wildfire hazard and reduce the potential danger from wildfire hazard to vulnerable populations.

Timeline 1-3 years
708
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-46 PH-1 Pandemic Response Plan
Mitigation Project Title Pandemic Response Plan
Project Description,
Issue/Background
The City shall develop a clear strategy that enhances the City’s pandemic and public health procedures in accordance with the CDC Guidelines. The strategy will be integrated into an updated Pandemic Response Plan that can be integrated into the EOP and Disaster Preparedness Plan. The Pandemic Response Plan will continue existing public health programs put in place during the COVID-19 pandemic, such as trace analytics and City staff health and safety protocols. The Pandemic Response Plan will identify vulnerable populations. It will also develop a framework for coordination among emergency management and public health agencies, such as the California Department of Public Health (CDPH), County of El Dorado, and Barton Memorial Hospital. A Pandemic Response Plan can cover ways to improve access to healthcare, internet, and other public health needs.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Public Health
Goals(s) Addressed Goal 1, 2, 3, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
City Manager’s Office
Partners CDPH, County of El Dorado, Barton Memorial Hospital Potential Funding General Fund
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action will help mitigate public health hazard.

Timeline 1-3 years
709
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-47 MH-1 Reverse 911 System
Mitigation Project Title Reverse 911 System
Project Description,
Issue/Background
The City shall maintain a reverse 911 system (i.e., automated phone system) to notify residents, employees, and visitors about emergencies and provide instructions. The City shall also study the feasibility of adding cellular telephone and email addresses to the system, in addition to listed and unlisted home telephone numbers. This action is an implementation program from the General Plan Health and Safety Element.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Multi-Hazard: Avalanches, Dam Incidents, Drought, Earthquakes, Flood, Landslide and Debris Flows, Severe Weather, Wildfire, Energy Shortages, Public Health Hazards
Goals(s) Addressed Goal 1, 2, 3, and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Police Department
Partners County of El Dorado, LVFPD
Potential Funding General Fund
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action will help notify civilians about emergencies timely.

Timeline 1-3 years
710
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-48 MH-2 Routine Local Hazard Mitigation Plan updates
Mitigation Project Title Routine LHMP updates
Project Description,
Issue/Background
The City shall regularly update the LHMP to incorporate the latest wildland fire and urban interface standards, identify hazards, minimize or eliminate their effects, and reduce prospective costs of reparations before any natural hazard takes place. This action is an implementation program from the General Plan Health and Safety Element.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Multi-Hazard: Avalanches, Dam Incidents, Drought, Earthquakes, Flood, Landslide and Debris Flows, Severe Weather, Wildfire, Energy Shortages, Public Health Hazards
Goals(s) Addressed Goal 1, 2, 3, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners
Potential Funding HMGP Funds
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action will ensure the ongoing process of the City’s hazard mitigation efforts.

Timeline 3-5 years
711
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-49 MH-3 Local Emergency Operations Plan review
Mitigation Project Title Local EOP review
Project Description,
Issue/Background
The City shall continue to periodically review and update the City’s Local EOP. The City EOP was last updated in 2021. The next update should occur before 2026. This action is an implementation program from the Health and Safety Element.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Multi-Hazard: Avalanches, Dam Incidents, Drought, Earthquakes, Flood, Landslide and Debris Flows, Severe Weather, Wildfire, Energy Shortages, Public Health Hazards
Goals(s) Addressed Goal 1, 2, 3, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners
Potential Funding General Fund
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action is an important component to ensure the ongoing process of the City’s hazard mitigation and emergency preparedness efforts.

Timeline 1-3 years
712
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-50 MH-4 Disaster Preparedness Plan
Mitigation Project Title Disaster Preparedness Plan
Project Description,
Issue/Background
The City shall maintain and regularly update, when necessary, the Disaster Preparedness Plan. This action is an implementation program from the General Plan Health and Safety Element.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Multi-Hazard: Avalanches, Dam Incidents, Drought, Earthquakes, Flood, Landslide and Debris Flows, Severe Weather, Wildfire, Energy Shortages, Public Health Hazards
Goals(s) Addressed Goal 1, 2, 3, 4 and 5
Priority (High, Medium,
Low)
High
Responsible Office/
Agency
Fire Department
Partners
Potential Funding General Fund
Cost Estimate $10,000 – $100,000
Benefits (Avoided
Losses)
This action is an important component to ensure the ongoing process of the City’s hazard mitigation and emergency preparedness effort.

Timeline 1-3 years
713
Chapter 5
Mitigation Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 5-51 MH-5 Examine Retrofitting Utilities to Below Ground Level and Analyzing Options with Local Utility Providers
Mitigation Project Title Examine Retrofitting Utilities to Below Ground Level and Analyzing Options with Local Utility Providers
Project Description,
Issue/Background
The City will examine retrofitting and undergrounding utilities, specifically electrical transmission and distribution line infrastructure by analyzing the options with the local utility providers.

Hazards Mitigated/
Lifelines Addressed
(include all that apply)
Multi-Hazard: Severe Weather, Wildfire, Energy Shortages Goals(s) Addressed Goal 1, 2, and, 4
Priority (High, Medium,
Low)
Medium
Responsible Office/
Agency
City Manager’s Office
Partners Liberty Utilities, Other Utility Providers
Potential Funding General Fund
Cost Estimate $50,000
Benefits (Avoided
Losses)
This action may result in increased reliability of service during severe weather events, high winds, or increased wildfire threat and enhances overall safety.

Timeline 1-3 years
714
Chapter 6
Plan Implementation and Maintenance
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 6-1 6 Plan Implementation and Maintenance

6.1 Adoption
DMA Requirements §201.6(c)(3):
[The local hazard mitigation plan shall include] documentation that the plan has been formally approved by the governing body of the jurisdiction requesting approval of the plan (e.g., City Council, county commissioner, Tribal Council).

The purpose of formally adopting this plan is to secure buy-in from City, raise awareness of the plan, and formalize the plan’s implementation. The adoption of this plan completes Planning Step 9 of the 10-step planning process: Adopt the Plan. The South Lake Tahoe City Council has adopted this LHMP plan by passing a resolution.

Implementation and maintenance of the plan is critical to the overall success of hazard mitigation planning. This is Planning Step 10 of the 10-step planning process. This section provides an overview of the overall strategy for plan implementation and maintenance, and outlines the method and schedule for monitoring, updating, and evaluating the plan. The section also discusses incorporating the plan into existing planning mechanisms and how to address continued public involvement.

6.2 Implementation
Once adopted, the plan faces the truest test of its worth: implementation. While this plan contains many worthwhile actions, the City will need to decide which action(s) to undertake first. Two factors will help with making that decision: the priority assigned the actions in the planning process, and funding availability. Low or no-cost actions most easily demonstrate progress toward successful plan implementation.

Implementation will be accomplished by adhering to the schedules identified for each action (see Section 5 for City mitigation actions), and through constant, pervasive, and energetic efforts to network and highlight the multi-objective, win-win benefits of each project to the City community and its stakeholders.

These efforts include the routine actions of monitoring agendas, attending meetings, and promoting a safe, sustainable community. The three main components of implementation are:
• Implement the action plan recommendations of this plan; • Utilize existing rules, regulations, policies and procedures already in existence; and • Communicate the hazard information collected and analyzed through this planning process so that the community better understands what can happen where, and what they can do themselves to be better prepared. Also, publicize the “success stories” that are achieved through the HMPC’s ongoing efforts.

During implementation of these efforts, it is important to maintain a constant monitoring of funding opportunities that can be leveraged to implement some of the more costly recommended actions. This will include creating and maintaining a bank of ideas on how to meet local match or participation requirements, should grants be pursued. When funding becomes available, the City will be in a position to capitalize on the opportunity. Funding opportunities to be monitored include special pre- and postdisaster funds, special district budgeted funds, state and federal earmarked funds, and other grant programs, including those that can serve or support multi-objective applications. 715
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Plan Implementation and Maintenance
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 6-2

6.2.1 Role of the HMPC in Implementation and Maintenance With adoption of this plan, the City will be tasked with plan implementation and maintenance. The HMPC agrees to:
• Act as a forum for hazard mitigation issues;
• Disseminate hazard mitigation ideas and activities to all stakeholders; • Pursue the implementation of high-priority, low/no-cost recommended actions; • Keep the concept of mitigation in the forefront of community decision making by identifying plan recommendations when other community goals, plans, and activities overlap, influence, or directly affect increased community vulnerability to disasters;
• Maintain a vigilant monitoring of multi-objective cost-share opportunities to help the community implement the plan’s recommended actions for which no current funding exists; • Monitor and assist in implementation and update of this plan; • Report on plan progress and recommended changes to the City Council and the governing boards of the other participating jurisdictions; and
• Inform and solicit input from the public.

The primary duty of the City is to see the plan successfully carried out and to report to their community governing boards and the public on the status of plan implementation and mitigation opportunities.

Other duties include reviewing and promoting mitigation proposals, considering stakeholder concerns about hazard mitigation, passing concerns on to appropriate entities, and posting relevant information on the City’s main website and LHMP webpage (and others as appropriate).

6.3 Maintenance and Monitoring
DMA Requirement §201.6(c)(4)(i):

The plan maintenance process shall include a] section describing the method and schedule of monitoring, evaluating, and updating the mitigation plan within a five-year cycle.

Plan maintenance implies an ongoing effort to monitor and evaluate plan implementation and to update the plan as required or as progress, roadblocks, or changing circumstances are recognized. This section describes how public participation will be integrated throughout the plan maintenance and implementation process. It also explains how the mitigation strategies outlined in this plan will be incorporated into existing planning mechanisms and programs, such as comprehensive land use planning processes, CIP project planning and building code enforcement and implementation. The plan’s format allows sections to be reviewed and updated when new data become available, resulting in a plan that will remain current and relevant.

6.3.1 Maintenance Schedule
In order to track progress and update the mitigation strategies identified in the action plan, the HMPC will revisit this plan at the following times or occurrences:
• Annually, to assess if mitigation actions/projects have been completed; • Following a significant-hazard event;
• Following a disaster declaration; or
• Any other time the HMPC sees it is prudent or necessary.

Annual Reviews: The HMPC will meet annually or after a disaster to assess progress on plan implementation. The City’s Fire Department (South Tahoe Fire Rescue) will facilitate these reviews and 716
Chapter 6
Plan Implementation and Maintenance
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 6-3 associated meetings. The timing of the annual meeting is recommended for the first or second quarter of each year to identify potential mitigation grants, some of which have a submittal period in the fourth quarter. A template for the annual meeting and a summary report is provided in Appendix E. Another tool developed during the 2021-2022 process to facilitate regular review and implementation and make the plan more of a “living document” is the City’s LHMP webpage that include the plan, risk assessment highlights, public announcements and updates, and links to the City’s GIS Webviewer and hazard maps.

Critical Facility Database Maintenance: Moving forward the City will maintain the critical facility database that was prepared during the 2021-2022 update. This database currently includes all City-owned buildings and infrastructure, in addition to key water and wastewater infrastructure owned and operated by two of the four utility providers in the City, including STPUD. The City’s GIS Manager will lead periodic reviews of the database and assess the need for updates, leveraging the LHMP webpage and GIS Webviewer.

Five-Year Update: This plan will be updated, approved, and adopted within a five-year cycle as per Requirement §201.6(c)(4)(i) of the DMA of 2000. Efforts to begin the update should begin no later than September 2025. The City will monitor planning grant opportunities from the Cal OES and FEMA for funds to assist with the update. This may include submitting a HMA planning grant application. This grant should be submitted in 2024, as there is a three-year performance period to expend the funds, and there is no guarantee that the grant will be awarded when initially submitted. This allows time to resubmit the grant in subsequent years, if needed. Updates to this plan will follow the most current FEMA and Cal OES planning guidance. The next plan update should be completed and reapproved by Cal OES and FEMA Region VIII by December 2026.The City can also update or revise the LHMP at anytime depending on annual reviews and changing priorities, not only every 5 years.

6.3.2 Maintenance and Evaluation Process
The HMPC will continually observe the incorporation process, evaluation method, updating method, continued public participation, and completion of the action/projects to assure that the HMPC and the plan itself are performing as anticipated. By monitoring these processes, the HMPC will then be able to evaluate them at the time of the plan update, determining if any changes are needed.

The LHMP plan update every five years provides an opportunity to determine whether there have been any significant changes in the City that may, in turn, necessitate changes in the types of mitigation actions proposed. New development in identified hazard areas, an increased exposure to hazards, the increase or decrease in capability to address hazards, and changes to federal or state legislation are examples of factors that may affect the necessary content of the LHMP.

The plan review provides City officials with an opportunity to evaluate those actions that have been successful and to explore the possibility of documenting potential losses that were avoided due to the implementation of specific mitigation measures. The plan review also provides the opportunity to address mitigation actions that may not have been successfully implemented as assigned.

During the five-year plan update process, the following questions will be considered as criteria for assessing the effectiveness and appropriateness of the Plan:
• Do the goals address current and expected conditions? • Are the goals and objectives consistent with changes in State and Federal policy? • Complete status update on all mitigation projects. What strategies should be revised? • Has the nature or magnitude of risks changed (current and expected conditions)? • Are the current resources appropriate for implementing the LHMP? 717
Chapter 6
Plan Implementation and Maintenance
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 6-4 • Are there implementation problems, such as technical, political, legal or coordination issues with other agencies?
• Have the outcomes occurred as expected?
• Did the City and other partners participate in the plan implementation process as assigned? The City is committed to involving the public in the continual reshaping and updating of the LHMP, as discussed in Section 6.3.4.

6.3.3 Incorporation into Existing Planning Mechanisms
Another important implementation mechanism that is highly effective and low-cost is incorporation of the LHMP recommendations and their underlying principles into other City plans and mechanisms. Where possible, the City and participating stakeholders in the region will use existing plans and/or programs to implement hazard mitigation actions. This plan should also be cross-referenced when related planning mechanisms are updated. As previously stated above, mitigation is most successful when it is incorporated into the day-to-day functions and priorities of government and development. As described in this plan’s capability assessment and jurisdictional annexes, the City already implement policies and programs to reduce losses to life and property from hazards. This plan builds upon the momentum developed through previous and related planning efforts and mitigation programs and recommends implementing actions, where possible, through these other program mechanisms.

These existing mechanisms include (but are not limited to) the following:
• City of South Lake Tahoe General Plan Health and Safety Element (2011) • Community service district area plans and master plans • City EOP
• City Ordinances (Floodplain Ordinance, Stormwater Ordinance, Grading Ordinance) • Flood/stormwater management/master plans (2013 Stormwater Management Plan 2008 Drainage Master Plan)
• Community wildfire protection plans (2015 Lake Tahoe Basin CWPP) • GSPs
• IRWMPs
• Stormwater Resource Plans
• UWMPs
• CIPs
• Other plans and policies outlined in the capability assessments in the jurisdictional annexes • Other plans, regulations, and practices with a mitigation focus HMPC members involved in the updates to the planning mechanisms will be responsible for integrating the findings and recommendations of this plan with these other plans, programs, etc., as appropriate. As an action step to ensure integration with other planning mechanisms, at the annual meeting of the HMPC described above in subsection 6.3.1 the City’s Fire Department Battalion Chief or designee will discuss where there are opportunities to incorporate the plan into other planning mechanisms and who would be responsible for leveraging those opportunities. HMPC members representing local stakeholders that represent state or regional agencies can also work with their planning teams, as appropriate to integrate identified mitigation actions into their own local plans and programs. For example, the Conservancy and TRPA may be able to integrate related wildfire and forest resiliency actions into their related plans. Efforts to integrate the hazard mitigation plan into City local plans, programs, and policies will be reported on at the annual HMPC plan review meeting, and a record of successful integration efforts will be kept. 718
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Plan Implementation and Maintenance
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 6-5 Efforts should continuously be made to monitor the progress of mitigation actions implemented through these other planning mechanisms and, where appropriate, their priority actions should be incorporated into updates of this LHMP.

Examples of a process for incorporation of the LHMP update into specific existing or upcoming planning mechanisms include:
• Adoption by reference or incorporation of this LHMP into the Health and Safety Element of the 2011 General Plan, as encouraged by AB 2140. Evidence of such adoption (by formal, certified resolution) shall be provided to Cal OES and FEMA to become eligible or maintain eligibility for California Disaster Assistance Act (CDAA) funding.
• Reference into the County of El Dorado LHMP.
• Incorporation into the City of South Lake Tahoe EOP.

6.3.4 Continued Public Involvement
Continued public involvement is imperative to the overall success of the plan’s implementation. Efforts will be made to involve the public in the plan maintenance, evaluation, and review process. This includes maintaining a digital version of the plan on the City Fire Department LHMP webpage for public review. In addition, information on who to contact within the OES will be posted with the plan. The City’s Fire Department staff will maintain a file of comments received for reference during the next five-year update.

Any revisions to the plan that may occur as a result of a disaster will also be made public and posted on the City’s LHMP webpage.

The next five-year update process also provides an opportunity to solicit participation from new and existing stakeholders and to publicize success stories from the plan implementation and seek additional public comment. A public hearing(s) or survey to receive public comment on the plan will be held during the plan update period. When the HMPC reconvenes for the update, they will coordinate with all stakeholders participating in the planning process, including those who joined the HMPC after the initial effort, to update and revise the plan. Public notice will be posted and public participation will be invited, at a minimum, through available website postings and press releases to the local media outlets as well as email and social media announcements.

Public involvement strategies that were used during the 2021-2022 planning process are captured in the Outreach Strategy in Appendix F. The appendix can serve as a reference for continued public involvement over the next several years and lays the foundation for outreach associated with the next formal five-year update.
719
Chapter 7
Plan Adoption
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 7-1 7 Plan Adoption
DMA Requirement §201.6(c)(5):
[The plan shall include...] Documentation that the plan has been formally adopted by the governing body of the jurisdiction requesting approval of the plan (e.g., City Council, County commissioner, Tribal Council).

7.1 Element E.1 Formal Adoption Documentation
Adoption by the local governing body demonstrates the community’s commitment to implementing the mitigation strategy and authorizes responsible agencies to execute their actions. The final plan is not approved until the City adopts the plan and FEMA receives documentation of the formal adoption. The City will submit this plan to the City Council upon successful completion of state and federal review and following the issuance of an Approved Pending Adoption (APA) designation from FEMA. This provides an efficient approval process if FEMA determines the LHMP update requires revisions because the City can make these revisions prior to initiating the local plan adoption process.

Once FEMA issues APA notification, adoption by the City must take place within one year to become or remain eligible for FEMA HMA program funding. Once the City records and submits the adoption documentation to Cal OES and FEMA, FEMA will issue an official approval letter stating the City has adopted and is approved and eligible for FEMA HMA program funding. The approval letter will include the expiration date five years from the date of the letter and attached to the approval letter will be a final FEMA Local Mitigation Plan Review Tool that provides feedback on the strengths of the plan, recommendations for plan improvements during future plan updates, and suggestions for implementing the mitigation strategy.
720
Chapter 8
References
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 8-1 8 References
"2 Lake Tahoe Ski Resorts Closed Due To High Winds; NWS Says 130 Mph Ridge Wind Gusts Possible". 2021. KTLA. https://ktla.com/news/california/2-lake-tahoe-ski-resorts-closed-due-to-highwinds-nws-warns-of-possible-130-mph-ridge-wind-gusts/. "4 Reasons Climate Change Is Here, Even Though It's Cold". 2021. Environmental Defense Fund. Accessed December 6. https://www.edf.org/card/4-reasons-climate-change-still-happening-despite-cold-weather. "About Lake Tahoe | U.S. EPA". 2021. U.S. EPA. Accessed December 10. https://www.epa.gov/laketahoe/about-lake tahoe#:~:text=It%20is%20recognized%20nationally%20and,under%20the%20Clean%20Water%20Ac t.

American Community Survey 1-Year & 5-Year Estimates Data Profile Arcuni, Peter. 2019. "Rivers In The Sky: What You Need To Know About Atmospheric River Storms | KQED".

KQED. https://www.kqed.org/science/1935067/rivers-in-the-sky-what-you-need-to-know-aboutatmospheric-river-storms. "Bubonic Plague". 2021. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/21590- bubonic-plague.

Cal-Adapt. 2018. LOCA Derived Data [GeoTIFF]. Data derived from LOCA Downscaled CMIP5 Climate Projections. Available at https://cal-adapt.org/.

California Demographic Data: State Department of Finance California Geological Survey, California Department of Conservation. https://www.conservation.ca.gov/cgs California Department of Forestry and Fire Protection Incidents Overview website. https://www.fire.ca.gov/incidents/
California Department of Forestry and Fire Protection website. https://www.fire.ca.gov/.

California Department of Water Resources. www.water.ca.gov/.

California Environmental Protection Agency, Department of Toxic Substance Control California Governor’s Office of Emergency Services. FY 2019-2020. Public Safety Power Shutoff Legislative Report. Available at
https://www.caloes.ca.gov/GrantsManagementSite/Documents/Public%20Safety%20Power%20Shutoff%2 0Legislative%20Report%20FY%202019-20.pdf.

California Governor’s Office of Planning and Research. The Integrated Climate Adaption and Resiliency Program. Impact Report and 2020 Program Recommendations.

California Natural Resources Agency. 2018. California’s Fourth Climate Change Assessment. Available at https://climateassessment.ca.gov/.

California Office of Emergency Services. 2018. California State Hazard Mitigation Plan. Available at https://www.caloes.ca.gov/cal-oes-divisions/hazard-mitigation/hazard-mitigation-planning/state-hazardmitigation-plan.

California Public Utilities Commission. https://www.cpuc.ca.gov/. 721
Chapter 8
References
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 8-2 California Register of Historic Places
California Tahoe Conservancy. 2019. Lake Tahoe Forest Action Plan.

California Tahoe Conservancy. 2020. Integrated Vulnerability Assessment of Climate Change in the Lake Tahoe Basin. Available at: https://tahoe.ca.gov/wp-content/uploads/sites/257/2020/04/IntegratedVulnerability-Assessment-of-Climate-Change-in-the-Lake-Tahoe-Basin_2020.pdf California Tahoe Conservancy. https://tahoe.ca.gov/.

California Wildfire & Forest Management Task Force. 2021. California’s Wildfire and Forest Resilience Action Plan.

Center for Disease Control and Prevention. https://www.cdc.gov/ Center for Western Weather and Water Extremes. https://cw3e.ucsd.edu/ City of South Lake Tahoe. 2011. General Plan. Available at https://www.cityofslt.us/575/General-Plan.

City of South Lake Tahoe. 2020. Climate Action Plan. Available at https://www.cityofslt.us/DocumentCenter/View/14460/SLT-CAP-DRAFT.

City of South Lake Tahoe. 2021. Emergency Operations Plan.

City of South Lake Tahoe. City Code/Ordinance. Available at https://www.codepublishing.com/CA/SouthLakeTahoe/.

City of South Lake Tahoe. Strategic Plan 2021 – 2026.

City of South Lake Tahoe website. https://www.cityofslt.us/ "Defensible Space / PRC 4291". 2021. Fire.Ca.Gov. Accessed December 1. https://www.fire.ca.gov/programs/communications/defensible-space-prc-4291/.

Diaz, Johnny. 2021. "Yes, Lake Tahoe Chipmunks Have Bubonic Plague. But Don’t Worry (Too Much).".

Nytimes.Com. https://www.nytimes.com/2021/08/05/us/chipmunks-bubonic-plague-tahoe-ca.html.

Douglas County (Nevada). 2019. Local Hazard Mitigation Plan.

Drought 2021 | El Dorado Irrigation District. 2022. Eid.Org. https://www.eid.org/customers/drought-2021.

El Dorado County. 2017. Climate Change and Health Profile Report El Dorado County. 2018. Local Hazard Mitigation Plan.

El Dorado Irrigation District website. https://www.eid.org/ El Dorado Local Agency Formation Commission (LAFCO). 2016. City of South Lake Tahoe Municipal Services Review and Sphere of Influence Update. Available at https://www.edlafco.us/files/369c08068/16May_Item4E_SouthLakeTahoeDraftMSR.pdf.

Federal Emergency Management Agency (FEMA). 2011. Local Mitigation Plan Review Guide.

FEMA Community Information System
FEMA. 2017. CRS Coordinators Manual.

FEMA. Flood Insurance Study for El Dorado County (September 26, 2008) FEMA. National Flood Hazard Layer for El Dorado County (April 3, 2012) Flood Emergency Information Exchange
722
Chapter 8
References
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 8-3 Homeland Infrastructure Foundation-Level Data (HIFLD)
Howard, Greyson. 2021. "Scientists Show Tahoe Is Home To Massive, If Less Well-Known Faults - Tahoe Quarterly". Tahoe Quarterly. Accessed December 6. https://tahoequarterly.com/tahoe-talk/scientistsshow-tahoe-is-home-to-massive-if-less-well-known-faults.

Howle, J., Bawden, G., Schweickert, R., Finkel, R., Hunter, L., Rose, R. and von Twistern, B., 2012. Airborne Lidar Analysis and Geochronology of Faulted Glacial Moraines in the Tahoe-Sierra Frontal Fault Zone Reveal Substantial Seismic Hazards in the Lake Tahoe Region, California-Nevada, USA. Geological Society of America Bulletin, 124(7-8), pp.1087-1101.

Jensen, Adam. 2010. "Winter Storm Knocks Out Power And Closes Highway". Tahoedailytribune.Com. https://www.tahoedailytribune.com/news/winter-storm-knocks-out-power-and-closes-highway/.

Lake Valley Fire Protection District. 2020. Local Hazard Mitigation Plan.

Lukins Brothers Water Company website. https://lukinswater.com/about-us/ National Drought Mitigation Center, University of Nebraska-Lincoln, Drought Impact Reporter National Drought Mitigation Center, University of Nebraska-Lincoln, U.S Drought Monitor National Flood Insurance Program, Community Status Book, 2020 National Interagency Fire Center. 2014. FAM-IT Portal. 2014 SIT Data.

National Interagency Fire Center. 2007. FAM-IT Portal. 2007 SIT Data.

National Inventory of Dams
National Pipeline Mapping System
National Register of Historic Places
National Renewable Energy Laboratory (NREL) Wind Prospector National Weather Service website
NOAA National Center for Environmental Information (NCEI) NOAA National Weather Service; World Climate
Pierce, D. W., J. F. Kalansky, and D. R. Cayan, Scripps Institution of Oceanography. 2018. Climate, Drought, and Sea Level Rise Scenarios for the Fourth California Climate Assessment. California’s Fourth Climate Change Assessment, California Energy Commission.
"Plague-Infested Chipmunks Force Closures Of South Lake Tahoe Attractions". 2021. KIRO 7. https://www.kiro7.com/news/trending/plague-infested-chipmunks-force-closures-south-lake-tahoeattractions/72MBEXERZ5GGVEKV2KB2HFEC5E/.

Pyrologix 2021
Robert T. Stafford Disaster Relief and Energy Assistance Act, Section 322 Schweickert, R., Moore, J., Lahren, M., Kortemeier, W., Kitts, C. and Adamek, T., 2019. The Tahoe-Sierra Frontal Fault Zone, Emerald Bay Area, Lake Tahoe, California: History, Displacements, and Rates.

Geosphere, 15(3), pp.783-819.
"Scientists Show Tahoe Is Home To Massive, If Less Well-Known Faults - Tahoe Quarterly". 2022. Tahoe Quarterly. https://tahoequarterly.com/tahoe-talk/scientists-show-tahoe-is-home-to-massive-if-less-wellknown-faults. 723
Chapter 8
References
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Page 8-4 Sierra Avalanche Center website. https://www.sierraavalanchecenter.org/ SGCRP, 2016: The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment. Crimmins, A., J. Balbus, J.L. Gamble, C.B. Beard, J.E. Bell, D. Dodgen, R.J. Eisen, N. Fann, M.D.

Hawkins, S.C. Herring, L. Jantarasami, D.M. Mills, S. Saha, M.C. Sarofim, J. Trtanj, and L. Ziska, Eds. U.S.

Global Change Research Program, Washington, DC, 312 pp.

South Tahoe Public Utility District 2015 Urban Water Management Plan South Tahoe Public Utility District 2020 Urban Water Management Plan South Tahoe Public Utility District 2020 Water Shortage Contingency Plan Southwest Climate and Environmental Information Collaborative (SCENIC).

State of California Office of Historic Preservation
Stewart, Susan I., Volker C. Radeloff, Roger B. Hammer, and Todd J. Hawbaker. Defining the Wildland Urban Interface. Journal of Forestry 105, no. 4 (2007): 201-207 Tahoe Keys Property Owners Association website. https://tkpoa.com/.

Tahoe Regional Planning Agency. 2012. Lake Tahoe Regional Plan.

The Tahoe Fire & Fuels Team. 2015. Lake Tahoe Basin Community Wildfire Protection Plan (CWPP).

Thomas, N., Mukhtyar, S., Galey, B., and Kelly, M. 2018. Cal-Adapt: Linking Climate Science with Energy Sector Resilience and Practitioner Need. Report prepared for California’s Fourth Climate Change Assessment. California Governor’s Office of Planning and Research, California Natural Resources Agency, and California Energy Commission
"Three Faults Under Lake Tahoe | Tahoetopia". 2021. Tahoetopia.Com. Accessed December 7. https://tahoetopia.com/news/three-faults-under-lake-tahoe.

UC Davis. 2020. 2020 State of the Lake Report. https://tahoe.ucdavis.edu/events/2020-state-lake-report UC Davis. 2021. 2021 State of the Lake Report.. https://tahoe.ucdavis.edu/events/2021-state-lake-report U.S. Census
U.S. Fish and Wildlife Service, Environmental Conservation Online System U.S. Department of Agriculture, Risk Management Agency Crop Indemnity Reports 2007-2020 U.S. Department of Agriculture, Sectary of Agriculture, Disaster Designations 2012-2020 U.S. Department of Homeland Security. Critical Infrastructure Security and Resilience Note: Winter Storms and Critical Infrastructure. 2014. Available at
https://www.npstc.org/download.jsp?tableId=37&column=217&id=3277&file=OCIA_Winter_Storms_and_ Critical_Infrastructure_141215.pdf.

United States Forest Service. 2016. Wildfire Risk to Communities Program.

United States Geological Survey. 2017. Quaternary Fault and Fold Database of the United States.

Westerling, Anthony LeRoy. “Wildfire Simulations for California's Fourth Climate Change Assessment:

Projecting Changes in Extreme Wildfire Events with A Warming Climate.” (2018).

Western Regional Climate Center (WRCC) data
World Health Organization. https://www.who.int/
724
Appendix A
Planning Team
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Appendix A: Hazard Mitigation Planning Committee
725
Appendix B
Planning Process Documentation
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Appendix B: Planning Process Documentation
726
Appendix C
Mitigation Categories and Alternatives
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Appendix C: Mitigation Strategy Meeting
727
Appendix D
Approval and Adoption Documentation
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Appendix D: Approval and Adoption Documentation
728
Appendix E
Annual Progress Meeting and Report Template
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Appendix E: Annual Progress Meeting and Report Template 729
Appendix F
Community Engagement Strategy
City of South Lake Tahoe Local Hazard Mitigation Plan | 2021 – 2026 Appendix F: Community Engagement Strategy
730
Prepared by:

Wood Environment & Infrastructure Solutions, Inc.
10940 White Rock Road, Suite 190
Rancho Cordova, California 95670
731
Resolution 2022-018
Adopted by the City of South Lake Tahoe
Planning Commission
October 13, 2022
Recommending that the City Council Adopt the South Lake Tahoe Local Hazard Mitigation Plan update as an Amendment by Incorporation by Reference into the Health and Safety Element of the City of South Lake Tahoe General Plan

BACKGROUND
A. The City of South Lake Tahoe recognizes the threat that natural hazards pose to people and property within our community; and
B. Undertaking hazard mitigation actions will reduce the potential for harm to people and property from future hazard occurrences; and
C. The U.S. Congress passed the Disaster Mitigation Act of 2000 ("Disaster Mitigation Act") emphasizing the need for pre-disaster mitigation of potential hazards; and D. The Disaster Mitigation Act made available hazard mitigation grants to state and local governments; and
E. An adopted Local Hazard Mitigation Plan (LHMP) is required as a condition of future funding for mitigation projects under multiple Federal Emergency Management Agency (FEMA) pre- and post-disaster hazard mitigation assistance grant programs; and
F. The City of South Lake Tahoe has met all federal requirements of the Stafford Act and applicable amendments, and has further met all the requirements of the Disaster Mitigation Act through stakeholder engagement by establishing a Hazard Mitigation Planning Committee and through public participation from online surveys and public workshops; and
G. The City of South Lake Tahoe fully participated in the FEMA-prescribed mitigation planning process to prepare this LHMP update; and
H. The California Office of Emergency Services (Cal OES) and FEMA Region IX officials have reviewed the City of South Lake Tahoe LHMP update and approved it contingent upon this official adoption of the participating governing body; Resolution 2022-018 October 13, 2022 Page 1 of 4
732
I. The City of South Lake Tahoe desires to comply with the requirements of the Disaster Mitigation Act and to augment its emergency planning efforts by formally adopting the City of South Lake Tahoe LHMP update; and
J. The City of South Lake Tahoe's Strategic Plan 2021-2026 includes priorities related to the Built Environment, Community for All, and Continuous Improvement that focus on carbon neutrality, inclusion and diversity, public safety, infrastructure and maintenance, and fiscal sustainability and resiliency; and K. The City of South Lake Tahoe's General Plan Health and Safety Element includes Policy HS-1 .9 Natural Hazard Mitigation Plan to "maintain and implement the Natural Hazard Mitigation Plan to identify natural hazards, minimize or eliminate their effects and reduce prospective costs of reparations before any natural hazard takes place."; and
L. Adoption by the governing body for the City of South Lake Tahoe, demonstrates the jurisdiction's commitment to fulfilling the mitigation goals and objectives outlined in this LHMP update; and
M. Assembly Bill (AB) 2140 provides cities the authority to adopt by reference their respective LHMP as part of the Safety Element of its General Plan and by doing so, a city becomes eligible for additional funding from the Cal OES under the California Disaster Assistance Act, and absent adoption of the LHMP into the Safety Element, maximum State funding from the OES is limited to 75% of the total cost of mitigation for qualifying events; and
N. Additional funding from Cal OES made available through this General Plan Amendment is in the public interest; and

0. The potential impacts and proposed changes due to the General Plan Amendment are not detrimental to the public health, safety, or welfare; and P. LHMP adoption legitimacies the plan and authorizes responsible agencies to carry out their responsibilities under the plan; and
Q. The adoption of the City of South Lake Tahoe LHMP update and as an amendment to the City of South Lake Tahoe General Plan Health and Safety Element incorporating the LHMP update is exempt from the California Environmental Quality Act (CEQA) pursuant to the following CEQA Guidelines sections each on a separate and independent basis: 15061 (b )(3) ( common sense exemption), 15183 (projects consistent with a community plan, general plan, or zoning), and 15162 (feasibility and planning studies). The common sense exemption applies only to projects which have the potential for causing a significant effect on the Resolution 2022-018
October 13, 2022 Page 2 of 4
733
environment, and it can be seen with certainty that there is no possibility that the activity may have a significant effect on the environment. Section 15183 categorically exempts projects that are consistent with the City's General Plan, Community Plans, and Zoning Ordinance; the adoption of the LHMP update and its incorporation into the General Plan by reference will not have a significant effect on the environment. Section 15162 exempts feasibility and planning studies; the LHMP update is a planning study that informs the City of vulnerabilities to natural hazards and develops potential future actions to mitigation risks. The adoption of the LHMP update and related Health and Safety Element Policy HS-1.9 is not a commitment to any future action, nor is it a decision to approve, adopt, or fund any of the potential mitigation actions identified in the plan.

BASED ON THE FACTS SET FORTH IN THE BACKGROUND, BE IT RESOLVED, that the Planning Commission of the City of South Lake Tahoe:

1. Finds that the action taken on this matter and recommendations made after consideration of the whole administrative record are consistent with Government Code Section 65853 et seq.; and

2. Recommends the City Council find that adoption of the LHMP is not a project subject to the requirements of the California Environmental Quality Act (CEQA) given the LHMP itself is a continuing administrative or maintenance activity, such as general policy and procedure making (i.e., Health and Safety Element Policy HS-1.9), or governmental administrative activity, and will not result in direct or indirect physical changes in the environment in accordance with Section 15378(b); and

3. Recommends the City Council also finds that adoption of the LHMP is categorically exempt based on the common sense exemption that CEQA applies only to projects which have the potential for causing a significant effect on the environment, and it can be seen with certainty that there is no possibility that the current activity may affect the environment, in accordance with Section 15061 (b )(3). Adoption of the LHMP is also exempt from CEQA in accordance with Section 15183 as a project that is consistent with the City's General Plan, Community Plans, and Zoning Ordinance; and/or categorically exempt from CEQA in accordance with Section 15162 as a feasibility and planning study that informs the City of vulnerabilities to natural hazards and develops potential future actions to mitigation risks; and

4. Recommends the City Council adopt the South Lake Tahoe LHMP update as an official plan; and

5. Recommends that the City Council amend the City General Plan Health and Safety Element Policy HS-1 .9 to reference the adopted LHMP:

Resolution 2022-018
October 13, 2022 Page 3 of 4
734
Policy HS-1 .9 Natural Local Hazard Mitigation Plan
Maintain and implement the l\.,latural Local Hazard Mitigation Plan to identify natural hazards, minimize or eliminate their effects and reduce prospective costs of reparations before any natural hazard takes place.

6. Recommends that the City Council authorize city staff to submit this adoption resolution to the Cal OES and FEMA Region IX officials to enable the plan's final approval in accordance with the requirements of the Disaster Mitigation Act of 2000 and to establish conformance with the requirements of AB 2140.

7. This resolution is effective immediately upon adoption Adopted by the City of South Lake Tahoe Planning Commission on October 13, 2022 by the following vote:

Yes: Feiger, Roberts and Willliams

Absent: Rahbeck and Wieczorek
Doug Williams, Vice Chair
Attest:

Sue Bl;iokeosbip mer J4 2022 J3·22 PDT'
Susan Blankenship, City Clerk
D Octl4,2022 ate: ___ _
The presence of electronic signature certifies that the foregoing is a true and correct copy as approved by the South Lake Tahoe Planning Commission.

Resolution 2022-018
October 13, 2022 Page4of4
735
Resolution 2022-018 Safety Element
lncoporation
Final Audit Report 2022-10-1 4
Created: 2022-10-14
By: jo Mcdonough [email protected])
Status: Signed
Transaction ID: CBJCHBCAABAA5RUg8ms6Ws7nm2JiGF _XXuCMmFy6Hz7b "Resolution 2022-018 Safety Element lncoporation" History t:l Document created by jo Mcdonough [email protected]) 2022-10-14- 8:04:58 PM GMT- IP address: 128.92.1 36.146 ~ Document emailed to Sue Blankenship ([email protected]) for signature 2022-10-14 - 8:05:59 PM GMT
t:l Email viewed by Sue Blankenship ([email protected]) 2022-10-14 - 8:22:08 PM GMT- IP address: 128.92.136.146 0'8 Document e-signed by Sue Blankenship ([email protected]) Signature Date: 2022-10-14- 8:22:22 PM GMT -Time Source: server- IP address: 128.92.136.146 ~ Document emailed to [email protected] for signature 2022-10-14 - 8:22:23 PM GMT
t:l Email viewed by dwilliams@cityofslt. us
2022-10-14 - 10:17:43 PM GMT- IP address: 47.36.1 18.94 0o Signer [email protected] entered name at signing as Douglas williams 2022-10-14 - 10:22:06 PM GMT- IP address: 47.36.11 8.94 0o Document e-signed by Douglas williams ([email protected]) Signature Date: 2022-10-14 - 10:22:08 PM GMT - Time Source: server- IP address: 47.36.118.94 0 Agreement completed.
2022-10-14 - 10:22:08 PM GMT
fl Adobe Acrobat Sign
736
Resolution 2022-XXX November 1, 2022 Page 1 of 4
Resolution 2022-XXX
Adopted by the City of South Lake Tahoe
City Council
November 1, 2022
Adopting the South Lake Tahoe Local Hazard Mitigation Plan update as an Amendment by Incorporation by Reference into the Health and Safety Element of the City of South Lake Tahoe General Plan

BACKGROUND
A. The City of South Lake Tahoe recognizes the threat that natural hazards pose to people and property within our community; and
B. Undertaking hazard mitigation actions will reduce the potential for harm to people and property from future hazard occurrences; and
C. The U.S. Congress passed the Disaster Mitigation Act of 2000 (“Disaster Mitigation Act”) emphasizing the need for pre-disaster mitigation of potential hazards; and D. The Disaster Mitigation Act made available hazard mitigation grants to state and local governments; and
E. An adopted Local Hazard Mitigation Plan (LHMP) is required as a condition of future funding for mitigation projects under multiple Federal Emergency Management Agency (FEMA) pre- and post-disaster hazard mitigation assistance grant programs; and
F. The City of South Lake Tahoe has met all federal requirements of the Stafford Act and applicable amendments, and has further met all the requirements of the Disaster Mitigation Act through stakeholder engagement by establishing a Hazard Mitigation Planning Committee and through public participation from online surveys and public workshops; and
G. The City of South Lake Tahoe fully participated in the FEMA-prescribed mitigation planning process to prepare this LHMP update; and
H. The California Office of Emergency Services (Cal OES) and FEMA Region IX officials have reviewed the City of South Lake Tahoe LHMP update and approved it contingent upon this official adoption of the participating governing body; 737
Resolution 2022-XXX November 1, 2022 Page 2 of 4
I. The City of South Lake Tahoe desires to comply with the requirements of the Disaster Mitigation Act and to augment its emergency planning efforts by formally adopting the City of South Lake Tahoe LHMP update; and
J. The City of South Lake Tahoe’s Strategic Plan 2021-2026 includes priorities related to the Built Environment, Community for All, and Continuous Improvement that focus on carbon neutrality, inclusion and diversity, public safety, infrastructure and maintenance, and fiscal sustainability and resiliency; and K. The City of South Lake Tahoe’s General Plan Health and Safety Element includes Policy HS-1.9 Natural Hazard Mitigation Plan to “maintain and implement the Natural Hazard Mitigation Plan to identify natural hazards, minimize or eliminate their effects and reduce prospective costs of reparations before any natural hazard takes place.”; and
L. Adoption by the governing body for the City of South Lake Tahoe, demonstrates the jurisdiction’s commitment to fulfilling the mitigation goals and objectives outlined in this LHMP update; and
M. Assembly Bill (AB) 2140 provides cities the authority to adopt by reference their respective LHMP as part of the Safety Element of its General Plan and by doing so, a city becomes eligible for additional funding from the Cal OES under the California Disaster Assistance Act, and absent adoption of the LHMP into the Safety Element, maximum State funding from the OES is limited to 75% of the total cost of mitigation for qualifying events; and
N. Additional funding from Cal OES made available through this General Plan Amendment is in the public interest; and
O. The potential impacts and proposed changes due to the General Plan Amendment are not detrimental to the public health, safety, or welfare; and P. LHMP adoption legitimacies the plan and authorizes responsible agencies to carry out their responsibilities under the plan; and
Q. The adoption of the City of South Lake Tahoe LHMP update and as an amendment to the City of South Lake Tahoe General Plan Health and Safety Element incorporating the LHMP update is exempt from the California Environmental Quality Act (CEQA) pursuant to the following CEQA Guidelines sections each on a separate and independent basis: 15061(b)(3) (common sense exemption), 15183 (projects consistent with a community plan, general plan, or zoning), and 15162 (feasibility and planning studies). The common sense exemption applies only to projects which have the potential for causing a significant effect on the environment, and it can be seen with certainty that there is no possibility that the 738
Resolution 2022-XXX November 1, 2022 Page 3 of 4
activity may have a significant effect on the environment. Section 15183 categorically exempts projects that are consistent with the City’s General Plan, Community Plans, and Zoning Ordinance; the adoption of the LHMP update and its incorporation into the General Plan by reference will not have a significant effect on the environment. Section 15162 exempts feasibility and planning studies; the LHMP update is a planning study that informs the City of vulnerabilities to natural hazards and develops potential future actions to mitigation risks. The adoption of the LHMP update and related Health and Safety Element Policy HS-1.9 is not a commitment to any future action, nor is it a decision to approve, adopt, or fund any of the potential mitigation actions identified in the plan.

BASED ON THE FACTS SET FORTH IN THE BACKGROUND, BE IT RESOLVED, that the City Council of the City of South Lake Tahoe:

1. Finds that the action taken on this matter and recommendations made after consideration of the whole administrative record are consistent with Government Code Section 65853 et seq.; and

2. Finds that adoption of the LHMP is not a project subject to the requirements of the California Environmental Quality Act (CEQA) given the LHMP itself is a continuing administrative or maintenance activity, such as general policy and procedure making (i.e., Health and Safety Element Policy HS-1.9), or governmental administrative activity, and will not result in direct or indirect physical changes in the environment in accordance with Section 15378(b); and

3. Further finds that adoption of the LHMP is categorically exempt based on the common sense exemption that CEQA applies only to projects which have the potential for causing a significant effect on the environment, and it can be seen with certainty that there is no possibility that the current activity may affect the environment, in accordance with Section 15061(b)(3). Adoption of the LHMP is also exempt from CEQA in accordance with Section 15183 as a project that is consistent with the City’s General Plan, Community Plans, and Zoning Ordinance; and/or categorically exempt from CEQA in accordance with Section 15162 as a feasibility and planning study that informs the City of vulnerabilities to natural hazards and develops potential future actions to mitigation risks; and

4. Adopts the South Lake Tahoe LHMP update as an official City plan; and

5. Amends the City General Plan Health and Safety Element Policy HS-1.9 to reference the adopted LHMP:

Policy HS-1.9 Natural Local Hazard Mitigation Plan
739
Resolution 2022-XXX November 1, 2022 Page 4 of 4
Maintain and implement the Natural Local Hazard Mitigation Plan to identify natural hazards, minimize or eliminate their effects and reduce prospective costs of reparations before any natural hazard takes place.

6. Authorizes city staff to submit this adoption resolution to the Cal OES and FEMA Region IX officials to enable the plan’s final approval in accordance with the requirements of the Disaster Mitigation Act of 2000 and to establish conformance with the requirements of AB 2140.

7. This resolution is effective immediately upon adoption Adopted by the City of South Lake Tahoe City Council on November 1, 2022 by the following vote:

Yes:

No:

Absent:

Abstain:
________________________ Date:_________
Devin Middlebrook, Mayor
Attest:
________________________
Susan Blankenship, City Clerk
The presence of electronic signature certifies that the foregoing is a true and correct copy as approved by the South Lake Tahoe City Council.
740
City of South Lake Tahoe
Local Hazard Mitigation Plan Update
City Council Hearing
November 1, 2022 – 9:00 AM
741
What is Hazard Mitigation?
• Any sustained action taken to reduce or eliminate long-term risk to human life and property from natural and human-caused hazards.

Mitigation Planning and Disaster Mitigation Act
2 City Council Hearing 742
Planning Process: FEMA’s 4-Phase Framework
Determine the
planning area and
resources
Build the Hazard
Mitigation Planning
Committee
Create an Community
Engagement Strategy
Review community
capabilities
Conduct a risk
assessment
Develop
mitigation
strategies
Keep the plan
current
Review and
adopt the plan
Create a safe
and resilient
community
Phase I
Phase II Phase III Phase IV
3 City Council Hearing 743
Phase I: Create Planning Team and Community Engagement Strategy 4 City Council Hearing
Requirement: Two Opportunities
- During drafting stage
- Prior to approval
Outreach Tools:
• City’s LHMP Webpage: https://www.cityofslt.us/LHMP
• Press Releases, Social Media Posts, TV Coverage
• “Community Conversations” – 2 Public Workshops
• Online Survey (English and Spanish versions)
• 30-day Public Review Draft LHMP
• Electronic Comment Form
• Coordination with the City’s Public Information Officer 744
Phase II: Risk Assessment
5 City Council Hearing 745
• 5 Goals, 9 Objectives, 31 Mitigation Actions organized by Hazard Type • 5 Multi-Hazard
• 1 Dam Incidents
• 1 Drought
• 2 Earthquake
• 1 Energy Shortages
Phase III: Mitigation Strategy
• 5 Flood
• 2 Landslide
• 4 Severe Weather
• 9 Wildfire
• 1 Pandemic

ALTER AVERT ADAPT AVOID
6 City Council Hearing 746
Phase IV: Plan Adoption and Implementation and Maintenance Review and Adopt the Plan
• Cal OES Review - complete
• FEMA Plan Review – underway
• Planning Commission Recommendation
• City Council Adoption – following “approvable
pending adoption” letter from FEMA
Keep the Plan Current
• Establish Plan Maintenance procedures
• Continue public involvement
Create a Safe and Resilient Community
• Implementing the plan to achieve mitigation goals
• Securing funding and assistance
7 City Council Hearing 747
Months 1-3
• Kick-Off Meeting
• Develop Planning Team
• Organize Resources
• HMPC Meeting #1
• Define Planning Area
• Engagement Strategy
• Online Survey
Months 4-6
• Public Workshop #1
• Risk Assessment
• HMPC Meeting #2
• Advertise Webpage and Plan Update
Months 7-9
• HMPC Meeting #3
• Finalize Goals and Objectives
• Mitigation Action Development
• 1
st Administrative Draft LHMP
Months 10-12
• 2
nd Administrative Draft LHMP
• Public Review Draft LHMP
• Notice of Availability of Draft LHMP
Months 13-14
• Public Workshop #2
• FEMA Region IX Mitigation Plan Review Tool
• Cal OES Review
Months 15-16
• FEMA Review
• Planning Commission Hearing
• City Council Adoption
• Project & Grant Close-Out
Snapshot of Schedule: Key Milestones
8 City Council Hearing 748
LHMP Format: Organization
1 Introduction
2 City Profile and Capability Assessment
3 Planning Process
4 Hazard Identification and Risk Assessment
- Hazard Identification
- Asset Summary
- Hazard Profiles and Risk Assessment
- Human-Caused, Human-Health, and Climate-Related
Hazard Profiles and Risk Assessment
5 Mitigation Strategy
6 Plan Implementation and Maintenance
7 Plan Adoption
8 References
9 City Council Hearing 749
Questions? Thank you!
Jim Drennan
Fire Chief/Project Manager
South Lake Tahoe Fire Rescue
[email protected]
(530) 542-6164
Juliana Prosperi, AICP
Project Manager

WSP USA
[email protected]
(916) 636-3200
750
8CD06 Public Notice LHMP - Page 2 of 2
751
City of South Lake Tahoe
Agenda Item Executive Summary
Joe Irvin, City Manager
Meeting Date: November 1, 2022
Agenda Item #: 15
Agenda Item: Presentation - Gun Laws and School Safety
Executive Summary: City Council will receive a presentation on existing gun laws at the local, state, and federal level including laws restricting the ability to legally purchase or possess a gun, and local programs adopted by other cities that place extra requirements and/or restrictions on gun ownership. The presentation will include discussion of local school safety measures as it relates to active shooter response and the Student Resource Officer (SRO) program in South Lake Tahoe.