City Council and Authorities Concurrent
August 27, 2024

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Figure Shake Maps

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COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
Figure 8-S.

SOO-Year Probabalistic
Earthquake Scenario Peak
Ground Acceleration
D Santa Clara Coun ty Boundary
o County Boundari es
~ Water Bodies & Channels
Modified Mercalli Scale,
Potential Shaking
I (Not Felt)
II-III (Weak)
IV (Light)
I
V (Moderate)
VI (Strong)
VII (Very Strong)
VIII (Severe)
IX (Violent)
l
X+ (Extreme)
Rnng of Model Results
I"Sl!fo Planning Area
~TETRATECH
Map Datil Sources: Santi1 Cllra County,
CalTrans, USDA, Hazus·MH 3.1
A shake Map is a representation of ground shaking produced by an earthquake. The information it presents is different from the earthquake magnitude and epicenter that are released after an earthquake because shake maps focus on the ground shaking resulting from the earthquake, rather than the parameters describing the earthquake source. An earthquake has only one magnitude and one epicenter, but it produces a range of ground shaking at sites throughout the region, depending on the distance from the earthquake, the rock and soil conditions at sites, and variations in the propagation of seismic waves from the earthquake due to complexities in the structure of the earth's crust. A shake map shows the extent and variation of ground shaking in a region immediately following significant earthquakes. 134 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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8 16
Miles
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Figure 8-4.
100·Year Probabalistic
Earthquake Scenario Peak
Ground Acceleration
Cl Santa Clara County Boundary
o County Boundaries
Water Bodies & Channe ls
Modified Mercalli Scale,
Potential Shaking
I (Not Felt)
II-III (Weak)
IV (Light)
V (Moderate)
VI (Strong)
VII (Very Strong)
VIII (Severe)
l
IX (Violent)
_ X+ (Extreme)
Range of Model Results
Inside Planning Area
~TETRATECH
Map Data Sources: Santa Clara County,
CarTrans, USDA, HazUS-MH 3.1
FIGURE 8-4. 100-YEAR PROBABILISTIC EARTHQUAKE SCENARIO PEAK GROUND ACCELERATION 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1135 /
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4 8

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COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
16 Figure 8·5.
500-Year Probabalistic
Earthquake Scenario Peak
Ground Acceleration
o Sanla Clara County Boundary
o County Boundaries
~l.:!y,; Wale r Bodies & Channels
Modified Mercalli Scale,
Potential Shaking
I (Nol Felt)
II-III (Weak)
IV (lighl)
V (Moderate)
VI (Strong)
VII (Very Strong)
I
VIII (Severe)
; IX (Violent)
l
X+ (Extreme)
Range of Model Results
Inside Planning Area
~TETRATECH
Map Data Sources: Santi Clara County,
CDITrans , USDA , Hazu5·MH 3.1
FIGURE 8-5. 500-YEAR PROBABILISTIC EARTHQUAKE SCENARIO PEAK GROUND ACCELERATION 136 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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FIGURE 8-3. HAYWARD M7.0 FAULT SCENARIO PEAK GROUND ACCELERATION 10/15/17 Santa Clara County Operational Area Mitigation Plan I
Figure 8·6.

Hayward M7.0 Fault
Scenario Peak Ground
Acceleration
Cl Santa Clara Counly Boundary
o Counly Boundaries
Waler Bodies & Channels
Modified Mercalli Scale,
Potential Shaking
I (Nol Felt)
II-III (Weak)
IV (Light)
V (Moderate)
VI (Strong)
VII (Very Strong)
VIII (Sevene)
IX (Violent)
l X+ (Extreme)
Range of Model Results
Inside Planning Area
~TETRATECH
Map Data Sources: Santa Cllra County,
CalT,.n •. USDA. USGS

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Ground motion and intensity maps are derived from peak ground motion amplitudes recorded on seismic sensors (accelerometers), with interpolation based on estimated amplitudes where data are lacking, and site amplification corrections. Color-coded instrumental intensity maps are derived from empirical relations between peak ground motions and Modified Mercalli intensity .

There are two types of scenario ground motion maps: a ShakeMap of median shaking for a fault rupture; and a map of simulated ground motions for a specified earthquake hypocenter and fault rupture. The latter is more like an earthquake event and presents more variability in ground motions than a scenario shake map.

Earthquake scenario maps describe the expected ground motions and effects of hypothetical large earthquakes for a region. The following scenarios were chosen for this plan:
• A Magnitude 7.0 on the Hayward Fault with an epicenter approximately 25 miles north of the City of Palo Alto. shows the simulated ground motion map. • A Magnitude 7.0 on the Calaveras Fault with an epicenter approximately 25 miles north of the City of Milpitas.
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Error! Reference source not found. shows the scenario ShakeMap.

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Figure 8-7.

Calaveras M7.0 Fault
Scenario Peak Ground
Acceleration
C1 Sonto Claro County BOllndary
L.J County Boundaries
Water Bodies & Channels
Modified Mercalli Scale,
Potential Shaking
I (Not Felt)
II-III (Weak)
IV (Light)
V (Moderate)
VI (Strong)
VII (Very Strong)
VIII (Severe)
I
IX (Violent)
X+ (Extreme)
Range of Model ReslIlis
Inside Planning Area
~TETRATECH
16 Map Dat3 Sourcts: Santa Cl.lro1 County ,
Miles CoIT .. n •• USDA . USGS
138 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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• A Magnitude 7.8 on the San Andreas Fault with an epicenter approximately 148 miles northwest of the City of Palo Alto.
4 8 16 ,, __ -=== _____ Mlles
Error! Reference source not found. shows the scenario ShakeMap. 10/15/17 Santa Clara County Operational Area Mitigation Plan I
Figure 8·8.

San Andreas M7.8 Fault
Scenario Peak Ground
Acceleration
Santa Clara County Boundary
o County Boundaries
Water Bodies & Channels
Modified Mercalli Scale,
Potential Shaking
t (Not Felt)
II-III (Weak)
IV (Light)
V (Moderate)
VI (Strong)
VII (Very Strong)
VIII (Severe)
l
IX (Violent)
X+ (Extreme)
Range of Madel Resuijs
Inside Planning Area
~TETR"TECH
Map Oata Sources: Santa Clara County,
CalTrans , USDA, USGS

4 OFFICE OF EMERGENCY SERVICES
COUNTY OF SANTA ClARA & SANTA ClARA COUNTY FIRE
8 16
Miles
Figure 8·9.

National Earthquake Hazard
Reduction Program Soli
Classifications
o Santa Claro County Boundary
o County Boundari es
Water Bodies & Channels
B I Rock
C 1 Very Dense Soil - So~ Rock
0 1 Stiff Soil
E 1 Soft Soil
~ TETRA TECH
FIGURE 8-4. NATIONAL EARTHQUAKE HAZARD REDUCTION PROGRAM SOIL CLASSIFICATIONS

NEHRP SOIL MAPS
NEHRP soil types define the locations that will be significantly impacted by an earthquake. NEHRP Soils Band C typically can sustain low-magnitude ground shaking without much effect. The areas that are most commonly affected by ground shaking have NEHRP Soils D, E and F.shows NEHRP soil classifications in the Santa Clara County OA.

LIQUEFACTION MAPS
Soil liquefaction maps are useful tools to assess potential damage from earthquakes . When the ground liquefies, sandy or silty materials saturated with water behave like a liquid, causing pipes to leak, roads and airport runways to buckle, and building foundations to be damaged. In general, areas with NEHRP Soils D, E and F are also susceptible to liquefaction. If there is a dry soil crust, excess water will sometimes come to the surface through cracks in the confining layer, bringing liquefied sand with it, creating sand boils. Error! Reference source not found. shows the liquefaction susceptibility in the Santa Clara County GA.

ALQUIST-PRIOLO ZONE MAPS
The sliding movement of earth on either side of a fault is called fault rupture. Fault rupture begins below the ground surface at the earthquake hypocenter, typically between 3 and 12 miles below the ground 140 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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surface in California. If an earthquake is large enough, the fault rupture will travel to the ground surface, potentially destroying structures built across its path (CaIOES, 2013).

California's Alquist-Priolo Zone maps define regulatory zones for potential surface fault rupture where fault lines intersect with future development and populated areas. The purpose of these maps is to assist in the geologic investigation before construction begins to ensure that structures will not be located on an active fault. The Santa Clara County OA is located in a designated Alquist-Priolo Zone for the Hayward Fault (California Department of Conservation, 2010).

Alquist-Priolo maps were referenced, but not specifically used, in the assessment of risk for this plan.

This plan assumes that the studies conducted and information provided by the State of California are the best available data for surface rupture risk and could not be improved through a separate assessment for this plan. Alquist-Priolo maps are available to the public on the California Department of Conservation website.

FREQUENCY
California experiences hundreds of earthquakes each year, most with minimal damage and magnitudes below 3.0 on the Richter Scale. Earthquakes that cause moderate damage to structures occur several times a year. According to the USGS, a strong earthquake measuring greater than 5.0 on the Richter Scale occurs every 2 to 3 years and major earthquakes of more than 7.0 on the Richter Scale occur once a decade. Both the San Andreas and the Hayward Faults have the potential for experiencing major to great events.

The USGS has created ground motion maps based on current information about fault zones. These maps show the PGA that has a certain probability (2 percent or 10 percent) of being exceeded in a 50-year period. The maps were most recently updated in 2014 with new seismic, geologic, and geodetic information on earthquake rates and ground shaking, representing the best currently available data. The 2014 map for California shows that for Santa Clara County, the PGA with a 10-percent probability of exceedance in 50 years is O.4g (see Figure 8-5).

The USGS estimated in 2016 that there is a 72-percent probability of at least one earthquake before 2043 with a magnitude of 6.7 or greater that could cause widespread damage in the San Francisco Bay area (USGS, 2015). California's state hazard mitigation plan (CalOES, 2013) cites projections that in the next 30 years there is more than a 99-percent probability of a Magnitude 6.7 earthquake in California and a 94-percent probability of a Magnitude 7.0 earthquake. Probabilities for earthquakes on major fault lines in the San Francisco Bay Area have been estimated by the USGS in its 2016 report, as summarized in Table 8-4.

TABLE 8-4. EARTHQUAKE PROBABILITIES FOR THE SAN FRANCISCO BAY AREA REGION, 2014-2043 Hunting Creek
Green Valley
Concord
Greenville
Berryessa
Calaveras
Maacama
Rodgers Creek Fault
Hayward
10/15/17
Fault I Proba bilit of One or More M~6. 7 Quake 2014-2043 16%
16%
16%
16%
16%
26%
8%
33%
33%
Santa Clara County Operational Area Mitigation Plan Page /141 San Andreas
San Gregorio
Source: USGS, 2015

SEVERITY

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Fault ! Probabll it of One or More M2:6.7 Quake 2014-2043 22%
6%
The severity of an earthquake can be expressed in terms of intensity or magnitude:
• Intensity represents the observed effects of ground shaking at any specified location. The intensity of earthquake shaking lessens with distance from the earthquake epicenter.

Tabulated peak ground accelerations for a listed "maximum credible earthquakes" are a measure of how a site will be affected by seismic events on distant faults. • Magnitude represents the amount of seismic energy released at the hypocenter of the earthquake. It is based on the amplitude of the earthquake waves recorded on instruments.

Magnitude is thus represented by a single, instrumentally determined value. 142 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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FIGURE 8-5. PEAK GROUND ACCELERATION WITH 10-PERCENT PROBABILITY OF EXCEEDANCE IN 50 YEARS ABAG estimates a potential loss of 159,000 housing units in Bay Area communities after a large earthquake. This loss would have disastrous effects on local and regional economies . Recovery, repair, and rebuilding time for each household would be lengthy because of the number of homes that would need repair or replacement.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1143

WARNING TIME

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There is no current reliable way to predict the day or month that an earthquake will occur at any given location. Research and beta testing are being done with warning systems that use telecommunications that can travel faster than an earthquake's high energy waves, called S waves. The warning is generated by a rupture at an earthquake's hypocenter and telecommunicated to provide a warning for shaking before the S waves arrive. These potential earthquake early warning systems could give up to approximately 40 seconds' notice of peak earthquake shaking. The warning time is very short, but it could allow for someone to get under a desk, step away from a hazardous material, or shut down a computer system.

SECONDARY HAZARDS
Earthquakes can cause large and sometimes disastrous landslides and mudslides. River valleys are vulnerable to slope failure, often as a result of loss of cohesion in clay-rich soils. Soil liquefaction occurs when water-saturated sands, silts, or gravelly soils are shaken so violently that the individual grains lose contact with one another and "float" freely in the water, turning the ground into a pudding-like liquid.

Building and road foundations lose load-bearing strength and may sink quicksand-like into what was previously solid ground. Unless properly secured, hazardous materials can be released, causing significant damage to the environment and people.

Earthen dams and levees are highly susceptible to seismic events, and the impacts of their eventual failures can be considered secondary risk exposure to earthquakes. Depending on the location, earthquakes can also trigger tsunamis. Additionally, fires can result from gas lines or power lines that are broken or downed during the earthquake. It may be difficult to control a fire, particularly if the water lines feeding fire hydrants are also broken. After the 1906 earthquake in San Francisco, for example, a fire burned for three days, destroying much of the city and leaving 250,000 people homeless (Michigan Tech University, no date).

EXPOSURE

POPULATION
The entire population of the OA is potentially exposed to direct and indirect impacts from earthquakes.

The degree of exposure is dependent on many factors, including the age and construction type of the structures people live in, the soil type their homes are constructed on, their proximity to fault location, etc. Whether directly impacted or indirectly impact, the entire population will have to deal with the consequences of earthquakes to some degree. Business interruption could keep people from working, road closures could isolate populations, and loss of functions of utilities could impact populations that suffered no direct damage from an event itself.

PROPERTY
According to Santa Clara County Tax Assessor records, there are 464,223 buildings in the OA, with a total replacement value of $477 billion. Since all structures in the OA are susceptible to earthquake impacts to varying degrees, this total represents the property exposure to seismic events. Table 8-5 shows the exposure value breakdown by municipality with the OA. 144 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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TABLE 8-5. EARTHQUAKE EXPOSURE BY MUNICIPALITY
JUrisdiction Total # of BUlldm s Total BUlldm Value-Structure and Contents Campbell 11,987 $11,181,660,749
Cupertino 16,413 $13,890,786,985
GiI~oy 13,1 44 $1M01,505,586
Los Altos 10,981 $8,825,187,782
Los Altos Hills 2,970 $3,242,710,721
Los Gatos 10,407 $10,893,322,460
Milpitas 1~J 242 $19,146,882,365
Monte Sereno 1,218 $872,909,228
Morgan Hill 11 ,974 $11,160,393.427
Mountain View 18,891 $25,062.452,472
Palo Alto 20,209_ $25.777,115,586
San Jose 235,552 $213,377,474,752
Santa Clara (city) 28,809 $43.398.577,930
Saratoga 10,830 1$8,143,761,638
Sunnyvale 31,915 $42,852,045,398
Unincor orated County 20,681 $25,352.649,992
mat 464223 .$116 WMf

CRITICAL FACILITIES AND INFRASTRUCTURE
All critical facilities in the OA are exposed to the earthquake hazard . Table 4-4 lists the number of each type of facility by jurisdiction. Hazardous materials releases can occur during an earthquake from fixed facilities or transportation-related incidents. Transportation corridors can be disrupted during an earthquake, leading to the release of materials to the surrounding environment. Facilities holding hazardous materials are of particular concern because of possible isolation of neighborhoods surrounding them. During an earthquake, structures storing these materials could rupture and leak into the surrounding area or an adjacent waterway, having a disastrous effect on the environment, or emit chemicals in a toxic plume.

ENVIRONMENT
Environmental problems as a result of an earthquake can be numerous. Secondary hazards will likely have some of the most damaging effects on the environment. Earthquake-induced landslides in landslide-prone areas can significantly damage surrounding habitat. It is also possible for streams to be rerouted after an earthquake . Rerouting can change the water quality, possibly damaging habitat and feeding areas. There is a possibility that streams fed by groundwater wells will dry up because of changes in underlying geology.

VULNERABILITY
Earthquake vulnerability data was generated using a Level 2 Hazus analysis. Once the location and size of a hypothetical earthquake are identified, Hazus estimates the intensity of the ground shaking, the number of buildings damaged, the number of casualties, the damage to transportation systems and utilities, the number of people displaced from their homes, and the estimated cost of repair and clean up. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1145

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POPULATION
There are estimated to be 34,006 people in 7,803 households living on soils with high to very high liquefaction potential in the OA, or about 1.8 percent of the total population. Impacts on persons and households in the OA were estimated for the 100-year and 500-year shaking from earthquakes and the three scenario events through the Level 2 Hazus analysis. Table 8-6 summarizes the results.

TABLE 8-6. ESTIMATED EARTHQUAKE IMPACT ON PERSONS
S N b f 0 I d H h Id Number of Persons ReqUiring Short-cenano um er 0 ISP ace ouse 0 s Term Shelter 100·Year Shaking .from Earthquakes 14,823 19,185
SOO·Year Shaking from Earthquakes 54,146 34,220
San Andreas ShakeMap Scenario 6,798 3,742
Calaveras Shake Map Scenario . 1,204 805
Hayward ShakeMap Scenario 7,258 4,403
The 100-year shaking results are less than the 500-year shaking results because stronger shaking occurs less often and is more likely to occur in a 500-year period than a 100-year period. The results for the Hayward fault simulation are larger than those for the San Andrea scenario because a simulation is more like a real event with more variable ground shaking than a ShakeMap, and stronger ground motions cause more damage. Therefore, it should not be concluded that a Hayward fault earthquake would be more damaging than a San Andreas fault earthquake in Santa Clara county . The relativity of these results is similar in the following property damage assessments.

PROPERTY
Building Age
Table 8-7 identifies significant milestones in building and seismic code requirements that directly affect the structural integrity of development. Using these time periods, the Core Planning Group used Hazus to identify the number of structures in the OA by date of construction.

TABL E 8-7. AGE OF STRUCTURES IN OA
I
Number of Current
Time Period OA Structures Significance of Time Frame
Pre·1933
1933·1940
1941·1960
1961·1975
1976·1994
1994· present
Tot~
I BUilt In Penod
17,185
6,416
,111,973
139,907
i 107,185
81,557
464223
Before 1933, there were no explicit earthquake requirements in building codes. State law did not require local govemments to have building officials or issue building permits.

In 1940, the first strong motion recording. was made.

In 1960, the Structural Engineers Association of California published guidelines on recommended earthquake provisions.

In 1975, significant improvements were made to lateral force requirements.

In 1994, the Uniform Building Code was amended to include provisions for seismic safety.

Seismic code is currently enforced.

The number of structures does not reflect the number of total housing units, as many multi-family units and attached housing units are reported as one structure. Approximately 17.6 percent of the OA's structures were constructed after the Uniform Building Code was amended in 1994 to include seismic 146 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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safety provisions. Approximately 3.7 percent were built before 1933 when there were no building permits, inspections, or seismic standards.

Soft-Story Buildings
A soft-story building is a multi-story building with one or more floors that are "soft" because of structural design. If a building has a floor that is 70-percent less stiff than the floor above it, it is considered a soft­ story building. This soft story creates a major weak point in an earthquake. Since soft stories are typically associated with retail spaces and parking garages, they are often on the lower stories of a building. When they collapse, they can take the whole building down with them, causing serious structural damage that may render the structure totally unusable.

These floors can be especially dangerous in earthquakes because they cannot cope with the lateral forces caused by the swaying of the building during a quake. As a result, the soft story may fail, causing what is known as a soft-story collapse. Soft-story collapse is one of the leading causes of earthquake damage to private residences .

Loss estimation and vulnerability analyses based on models with specified fragility curves for soft-story construction in the OA are not currently not available to support quantitative analyses of risk. There are qualitative reports on risk available within the OA. These reports were not used for this analysis due to their lack of quantitative data. ABAG and other agencies in the Bay Area have programs generating this type of data, but it is not known when such data will be available for the Santa Clara County OA. This type of data will need to be generated to support future risk assessments of the earthquake hazard.

Unreinforced Masonry Buildings
Umeinforced masomy buildings are constructed from materials such as adobe, brick, hollow clay tiles, or other masomy materials and do not contain an internal reinforcing structure, such as rebar in concrete or steel bracing for brick. Umeinforced masomy poses a significant danger during an earthquake because the mortar holding masonry together is typically not strong enough to withstand significant earthquakes.

Additionally, the brittle composition of these houses can break apart and fall away or buckle, potentially causing a complete collapse of the building.

In the Santa Clara County OA, umeinforced masomy buildings are generally brick buildings that were constructed before modern earthquake building codes and designs were enacted. The State of California enacted a law in 1986 that required all local governments in Seismic Zone 4 (nearest to active earthquake faults) to inventory umeinforced masomy buildings. The law encourages local governments to adopt local mandatory strengthening programs, delineate seismic retrofit standards, and put into place measures to reduce the number of people in umeinforced masomy buildings.

According to ABAG, housing units in umeinforced masomy buildings account for only 1-percent of the total Bay Area housing stock and 2.9-percent of the total Bay Area multi-family stock. loss Potential
Property losses were estimated through the Level 2 Hazus analysis for the 100-year and SOD-year earthquakes and the three scenario events. Table 8-8 through Table 8-12 show the results for two types of property loss:
• Structural loss, representing damage to building structures. • Non-structural loss, representing the value of lost contents and inventory, relocation, income loss, rental loss, and wage loss.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1147

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TABLE 8-8. Loss ESTIMATES FOR 100-YEAR PROBABILISTIC EARTHQUAKE JUrisdiction Estllnated Lo~ Assoclated~ \,II/~h Earthg~.Hl_ke_ ___ I % of Total Replacement Structure Contents Total I Value
Campbell $505,996,427 $169,701,861 $675,698,288 6.0%
Cupertino $472,758,374 $149,906,631 $622,665,005 4.5%
Gilroy $987,983,263 $335,108,563 $1,323,091,826 9.9%
Los Altos $214,771 ,634 $69,176,386 $283,948,020 3.2%
Los Altos Hills $47,488,693 : $15,366,287 $62,854,981 1.9% Los Gatos $409,842,678 $128,919,536 $538,762,214 4.9%
Milpitas $1,463,680,416 $545,788,776 $2,009,469,193 10.5% Monte Sereno $20,976,126 $6,568,989 $27,545,114 3.2%
Morgan Hill $632,735,072 .$231,755,018 $864,490,090 7.7% Mountain View $977 ,754,443 $366,874,887 $1 ,344,629,330 5.4% Palo Alto $765,915,867 ' $264,705,357 $1,030,621,224 4.0% San Jose $12,478,614,024 $4,258,371,674 $16,736,985,698 7.8% Santt! Clara (city) $2,233,949,303 $853,038,669 $3,086,987,972 7.1% Saratoga $232,740,429 ' $71,128,743 $303,869,171 3.7%
Sunnyvale $2,293,623,291 , $866,490,416 $3,160,113,707 7.4% Uninco orated County $1,195,998,097 $1,624,629,273 6.4% Total $2 934,828 136 $33696,381,106 7.104
TABLE 8-9. Loss EsTIMATES FOR 500-YEAR PROBABILISTIC EARTHQU AKE J d Estimated Loss Associated With Earthquake l°/c, of Total Replacement UriS Ictlon Structure Contents Total Value Campbell $1,438,806,333 $501,460,207 $1,940,266,541 17.4% Cupertino $1,493,375,153 $481,454,968 $1,974,830,121 14.2% Gilroy $2,125,578,652 $766,191,462 $2,891,770,114 21 .6% \
Los Altos $660,942,324 $213,836,429 $874,778,753 9.9%
Los Altos Hills $269,561,245 $83,572,523 $353,133,768 10.9% Los Gatos $1,565,681,355 $499,357,070 1$2,065,038,425 19.0% Milpitas $3,453,277,477 $1,336,817,335 1$4,790,094,811 :25.0% Monte Sereno $81,828,223 $26,022,814 $107,851,037 12.4% Morgan Hill $1,556,183,963 $598,989,430 $2,155,173,394 119.3% Mountain View $2,714,834,855 $999,369,227 $3,714,204,082 14.8% Palo Alto $3,121,522,448 $1,119,984,940 $4,241,507,389 .16.5% San Jose $30,697,874,311 $10,721,388,274 $41.419,262,585 19.4% Santa Clara (city) $6,109,242,405 $2,436,086,086 $8,545,328.491 : 19.7% Saratoga $782,305,711 1$237,727,257 $1,020,032,967 .12.5% Sunnyvale $2,099,320,754 $7,601,611,623 : 17.7%

20.1%
~8 . 6%
148 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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. TABLE 8-10. Loss ESTIMATES FOR SAN ANDREAS FAULT SCENARIO EA RTHQUAKE I Estimated Loss Associated with Earthquake I % of Total Replacement J unsdlctlon Structure Conte nts Total Value Campbell $266,361,593 $91,939,167 $360,320,780 13.4%
Cupertino $394,93,8,106 $121,571,712 $516,509,620 3.7%
Gilroy $419,064,648 $117,867,975 $536,932,623 14.0%
Los Altos $168,040,477 $60,915,166 $228,955,644 2.6%
Los Altos Hills $73.012.402 $26.086,665 $99,099,067 3.1% Los Gatos $551.147.772 $160.453,296 $711.601.068 6.5%
Milpitas $217,482,059 $84,942,479 $302,424,538 1.6%
Monte Sereno $25,384.893 $7,985,652 $33,370,545 3.8%
Morgan Hill $167,134,435 $55,290,307 $222,424,742 2.0%
Mountain View $729.409,216 . $250,935,763 $980,344,980 3.9% Palo Alto $822,534,220 $277,726,356 $1,100,260,576 4.3% San Jose $3,651 ,329,465 $1,178,457,733 $4,829,787,198 2.3% Santa Clara (city) $937.119,157 $318,839.374 $1 .255.958.531 2.9% Saratoga $275.758,169 $67.183,618 $362,941,987 4.5%
Sunnyvale $1 ,070.982,765 $349,525,192 $1,420,507,957 3.3% Unincorporated County 5.0%
Total &a
TABLE 8-11. Loss ESTIMATES FOR HAYWARD FAULT SCENARIO EARTHQUAKE JUriSdiction Estl,l!lated bo.-?s Associated with Earth~.l§~~ _____ I % of Total Replacement Structure Contents Total Value
Campbell $145,652,171 $57,004,474 $202,656,645 1.6%
Cupertino $157,615,263 $63,067,552 $220.682,835 '1.6%
Gilroy $155,997,953 $56,596,414 $214,594,367 :1.6%
Los Altos $105,557,744 , $39,945,699 $145,503,444 1.6%
Los Altos Hills $18,928,887 $7,258,126 $26,187,013 :0.8% Los Gatos , $75,310,084 $26,707,690 $104.017,775 1.0%
Milpitas $1,324,794,294 $457,349,460 $1.782, 143 , 7~ 4 9.3% Monte Sereno $4,498,438 $1,533,500 $6,031,938 :0.7%
Morgan Hill $62,285,636 $26 ,761,682 $89,047,518 :0.8%
Mountain View $472,591,853 $177,400,300 $649,992,154 2.6% Palo Alto $393,537,058 $150,658,781 $544,195,839 2.1%
San Jose : $7,036,459,632 $2,307,273,557 $9,343,733,189 4.4% Santa Clara (city) $1,262,160,116 $513,816,630 $1,775,976,946 4.1% Saratoga . $61,159,729 $22,344,258 $63.503,966 1.0%
Sunnyvale $919,597,590 . $330,574,618 $1,250,172,208 2.9% Unincorporated County $316,852,862 $122.271.622 $439,124,484 1.7% Total .. ~ $4 3&4 564 564 $1 3 ..
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TABLE 8-12. Loss ESTIMATES FOR CALAVERAS FAULT SCENARIO EARTHQUAKE I Estimated Loss Associated with Earthguake % of Total Replacement JUriSdiction . - - -- -- -- - -- -~ - - ~- - - Structure Contents Total I Value
Campbell $41,154,055 $20,587,484 $61,741,540 0.6%
Cupertino $35.648.046 $18,035,203 $53,683,249 0.4%
Gilroy 1$375,692/676 $118,641,437 $494,334,113 3.7%
Los Altos $15.658.147 $8,570.989 $24.229,136 0.3%
Los Altos Hills $3.450,136 $1 ,723,990 $5,174,126 0.2%
Los Gatos $24,305,779 $12,714,053 $37,019.832 0.3%
Milpitas $346,665,577 $129,750,710 ! $476,416,287 2.5%
Monte Sereno $1,299,175 $684,311 . $1 ,983,486 0.2%
Morgan Hill $248,724,109 $84,812,585 ~333 , 536,695 3.0% Mountain View $84,101,436 $44,618,612 $128,720,048 0.5% Palo Alto $56,714,344 $32,020,983 $88,735,327 0.3%
San Jose $2,356,423,562 $931.175,892 $3,287,599,454 1.5% Santa Clara (city) $290,057,384 $147,835,571 $437,892,955 1.0% Saratoga $13,423,753 $6,859,950 $20,283.703 -0.2%
Sunnyvale $219,546,926 $113,196,728 $332,743,654 0.8%
Unincorporated Count $318,804,780 $122.154.165' $440,958,945 1.7% oi.I $4,431,669 885 $1 793,382 684 $6 225,052.549 1.3%
A summary of the property-related loss results is as follows:
• For a lOO-year probabilistic earthquake shaking, the estimated damage potential is $33.7 billion, or 7.1 percent of the total replacement value for the OA. • For a SOD-year probabilistic earthquake shaking, the estimated damage potential is $88.8 billion, or 18.6 percent of the total replacement value for the OA. • For a 7.0-magnitude event on the San Andreas Fault, the estimated damage potential is $14.2 billion, or 3 percent of the total replacement value for the OA. • For a 7.0-magnitude event on the Hayward Fault, the estimated damage potential is $16.9 billion or 3.5 percent of the total replacement value for the OA. • For a 7.8-magnitude event on the Calaveras Fault, the estimated damage potential is $6.2 billion, or 1.3 percent of the total replacement value for the OA.

The Hazus analysis also estimated the amount of earthquake-caused debris in the OA for the lOO-year and SOD-year earthquakes and the three scenario events, as summarized in Table 8-13.

TABLE 8-13. ESTIMATED E ARTHQUAKE-CAUSED DEBRIS
Scenario DebriS to Be Removed tons )
100·Year Earthquake
500·Year Earthquake
San Andreas Fault Scenario
Hayward Fault Scenario
Calaveras Fault Scenario
150 I Page
8,341.19
21 ,207.49
4,044.37

4.270.05

1.203.24
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CRITICAL FACILITIES AND INFRASTRUCTURE
Level of Damage
Hazus classifies the vulnerability of critical facilities to earthquake damage in five categories: no damage, slight damage, moderate damage, extensive damage, or complete damage. The model was used to assign a vulnerability category to each critical facility category in the OA. The analysis was performed for the 100-year and SOO-year events and for all three fault scenarios. Results are summarized in Table 8-14 through Table 8-18.

TABLE 8-14. ESTIMATED DAMAGE TO CRITICAL FACILITIES FROM 100-YEAR EARTI-IQUAKE I Damage Probabilities (%) Type of Critical FacIlity - - - - . - - None Sli ht Moderate ExtenSive Com lete
Emergency Response I Public Health & Safety 59.01% 30.28% 8.75% 1.52% 0.42% Infrastructure lifeline 79.27% 10.18% 4.90% 3.89% ;1.73% Military Facilities 5.29% 58.86% 23.57% 9.58% 12.67%
~e~~v_~ryJa~ilitie~ __ 10.23% 23.93% 34.44% 23.62% 7.76% Socioeconomic Facilities 36.79% 33.26% 24.07% 1.28%
Hazardous Materials 17.65% 14.23% 38.53% 18.51%
Ovetldl .34.7% 28.5% 2204% 3.7%
Notes:

Damage level represents the highest-probability damage state for each facility Values shown are accurate for comparison of results in this plan. See Section 0 for discussion of data limitations.

TABLE 8-15. ESTIMATED DAMAGE TO CRITICAL FACILITIES FROM 500-YEAR EARTHQUAKE Damage Probabi lities (%) Type of Critical Facility -. - None Sli ht Moderate ExtenSive Com plete
Emerg~ncy Re~ponse I Public Health~ Safety 33.65% 41.57% 18.60% 3.58% 2.58% Infrastructure Lifeline 41.97% 16.59% 11.75% 15.12% 14.54% Military Facilities 0.86% 33.45% 31.05% 22.42% 12.19%
Recovery Facilities iO.73% 7.16% 18.27% 31.65% 42.17%
Socioeconomic Facilities 14.58% 25.17% 17.14% 11.63%
Hazardous Materials 0.92% 1.51% 35.48%
CMta1f 15.5% 2fl~A
Notes:

Damage level represents the highest-probability damage state for each facility Values shown are accurate for comparison of results in this plan. See Section 0 for discussion of data limitations. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1151

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TABLE 8-16. ESTIMATED DAMAG E TO CRITICAL F ACIUTIES FROM HAYWARD FAULT . I Damage Probabilities (%) Type of Critical FaCility --- - .. - - ~---- - -. - -- - - .

None SI! ht i Moderate ExtenSive Com lete
Emergency Response I Public Health & S~fety 71.42% '24.54% 3.20% 0.72% 0.09% Infrastructure Lifeline 84.93% 7.97% 3.49% 2.53% 1.06%
Military Facilities 7.07% 162.40% 20.98% 7.64% 1.89%
Recovery Facilities 9.45% 30.59% 39.02% 19.16% 1.76%
Socioeconomic Facilities 45.68% 37.92% 14.57% 1.69% 0.13% Hazardous Materials 34.33% 21 .99% 32.50% 9.98% 1.18%
averaU 42.1'1, aO.9% 19.0% 7.0% 1.0%
Notes:

Damage level represents the highest-probability damage state for each facility Values shown are accurate for comparison of results in this plan. See Section 0 for discussion of data limitations.

TABLE 8-17. ESTIMATED DAM AGE TO CRITICAL FACIUTIES FROM SAN ANDRE AS FAULT I Damage Probabilities 1%2 Type of Cntlcal FaCility --- - - - - .. \..- - --- -------- None Sli ht Moderate ExtenSive Com lete
Emergency Response I Public Health & Safety 84.28% 13.09% Infrastructu re Lifeline 88.39% 7.01%
Military Facilities 7.07% 62.40%
Recovery Facilities 35.99% 35.29%
Socioeconomic Facilities 59.68% 29.35%
Hazardous Materials 14.67% 20.40%
Overa1l 48.3% 2.7. 0/0
Notes:

Damage level represents the highest-probability damage state for each facility ,

2.36%

2.63%

20.98%

22.64%

10.32%

49.77%

18.1%

0.24%

1.48%

7.64%

5.49%

0.61%

14.09%
i&%
Values shown are accurate for comparison of results in this plan. See Section 0 for discussion of data limitations.

TABLE 8-18. ESTIMATED DAMAGE TO CRITICAL F ACIU TIES FROM CALAVER AS

0.01%
. 0.47%

1.89%

0.57%

0.02%

1.05%
e.7~
iDamane Probabilities (%) Type of Cntlcal FaCility _. - "--- - ~--.- --- - -. -- None Sli ht Moderate ExtenSive Com lete
Emergency Response I Public Health & Safety 90.24% 8.66% 0.99% 0.09% 0.00% Infrastructure Lifeline 93.78% 4.14% 1.22% 0.65% 0.19%
Military Facilities 16.11 % !67.77% 12.42% 3.15% 0.53%
Recovery Facilities ·33.15% 39.76% 23.25% 3.34% 0.49%
Socioeconomic Facilities 78.26% 19.10% 2.57% 0.06% 0.00% Hazardous Materials 62.94% 20.18% 15.79% 1.04% 0.03%
raO 8204% 2U% 9:4% 1.4'% 0.2%
Notes:

Damage level represents the highest-probability damage state for each facility Values shown are accurate for comparison of results in this plan. See Section 0 for discussion of data limitations. 152 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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Time to Return to Functionality
Hazus estimates the time to restore critical facilities to fully functional use. Results are presented as probability of being functional at specified time increments: 1, 3, 7, 14, 30 and 90 days after the event. For example, Hazus may estimate that a facility has 5 percent chance of being fully functional at Day 3, and a 95-percent chance of being fully functional at Day 90. The analysis was performed for the 100-year and 500-year events and for all three fault scenarios. Results are summarized in Table 8-19 through Table 8-23.

TABLE 8-19. FUNCTIONALITY OF CRITICAL FACILITIES FOR 100-YEAR EVENT I # of I Probabil ity-of Bel ngJ'"~tlonal (<>j~
Type of Cntlcal FacIlity Cntlcal D D ,at Day at Day
Facilities at ay 1 at ay 3 lat Day 7 [14 90
Emergency Response I Public Health & Saf~ty 288 59.0 59.7 88.6 89.3 198.0 99.3 Infrastructure Lifeline 1500' 87.6 91.0 93.2 93.4 94.8 97.2 Military Facilities 1 74.7 85.9 89.8 90.3 91.4 96.0
Recovery Facilities 4 :24.9 29.1 42.5 42.7 70.3 191.8
1382 36.7 37.9 _ ! ~9.5 i70.0 94.1 198.4
374 31.8 31.8 70.4 91.4

3.549 69:2 69.6 86.5 96.7
TABLE 8-20. FUNCTIONALITY OF CRITICAL FACILITIES FOR 500-YEAR EVENT 1# of IProbabili t . ~ Being Full Functlonal_ ~ __ _
Type of Cntlcal Facility Cntlcal I I-:: at Day at Day at Day Facilities at Day 1 at Day 3 I at Day 7 14 30 90
Emergency Response I Public Health & Safety 288 33.6 34.5 74.2 75.2 93.8 96.3 Infrastructure Lifeline 1500 58.3 65.6 70.0 70.8 72.8 81.7 Military .Facilities 50.7 65.6 71 .1 72.2 75.0 86.7
Reco,,-ery. Facilities 4 10.2 13.7 17.0 17.4 29.4 58.0
Socioeconomic Facilities 1382 14.5 15.2 39.2 39.7 71.2 87.3 374 0.9 0.9 2.4 2.4 .15.4 50.9
3549 28.0 32.6 45.6 46.3 59.6 76.8
TABLE 8-21. FUNCTIONALITY OF CRITICAL FACILITIES FOR HAYWARD FAULT 1# of l.ErObabllit of Being ~ Func~o~L- ~ __
Type of Cntlcal FacIlity Cntlcal -----:-Jat Day at Day at Day Facilities at Day 1 at Day 3 at Day ( 114 30 90
Emergency Response I Public Health & Safety 288 71.4 72.0 95.4 95.9 99.1 99.8 Infrastructure Lifeline 1500 91.1 93.5 95.4 95.6 96.7 98.2 Military Facilities 1 78.6 88.6 92.1 92.4 93.3 97.0
Rec()very Facilities 4 27.3 , ~Q: 5 45.6 45.8. 79.7 97.9 Socioeconomic Facilities 1382 45.6 47.0 83.1 183.5 98.1 99.8 374 34.3 '35.3
3549 58.0 61.1
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TABLE 8-22. FUNCTIONALITY OF CRITICAL FACILITIES FOR SAN ANDREAS FAULT I # of I Pro~tJility- of Belng . ~y£uQ.~I~~aH'&l _ _ ____ _ Type of Critical Facility Critical I at Day at Day at Day FacIlities at Day 1 at Day 3 at Day 7 14 30 90
Ernergen~y Response! Public Health.& ~afety ,288 84.3 84.6 97.1 97.3 99.7 99.9 Infrastructure Lifeline 1500 93.4 95.3 97.1 97.2 98.2 99.1 MJlit ~.ry f.aciliti~s 1 78.6 88.6 92.1 92.4 93.3 97.0 ----- - ---- ---- -- -- --- - Recovery Facilities 4 53.8 57.3 76.9 no 94.6 99.1
Socioeconomic Facilities 1382 59.6 60.8 188.7 89.0 99.3 99.9 374 14.6 15.6 '35.0 35.0 84.8 98.9
3549 e4.1 61.0 81.1 81.3 95.0 99.0
TABLE 8-23. FUNCTIONALITY OF CRITICAL FACILITIES FOR CALAVERAS FAULT I # of Probability of Being Fully Functional (%)
Type of Critical Facility Critical I at Day at Day at Day Facilities at Day 1 at Day 3 at Day 7 14 30 90
Emergency Response I Public Health & Safety 288 90.2 90.4 98.7 98.8 99.8 99.9 Infrastructu re Lifeline 1500 96.7 97.7 98.8 98.8 99.2 99.6 Military Facilities 89.0 94.9 96.9 97.1 97.4 98.9
Reco"ery Facilitills 4 51.0 54.7 78.5 78.6 96.8 99.2
Socioeconomic Facilities 1382 178.2 79.0 97.1 97.3 99.8 99.9 374 62.9 63.8 83.0 83.1 98.9 99.9
3 78.0 80.1 92.2 92.3 98.7 99.6
Hazardous Materials
An earthquake can cause hazardous material releases from fixed facilities and transportation-related releases.

Transportation
Liquefaction, landslides and fault surface rupture during an earthquake can significantly damage roads.

Access to major roads is crucial to life and safety after a disaster event as well as to response and recovery operations. Disruptions in transportation systems are of particular concern in areas with limited access via transportation corridors, as a major event has the potential to isolate these communities from critical assistance and aid.

Bridges
Earthquake shaking, liquefaction and landslides can significantly damage bridges, which often provide the only access to some neighborhoods. Since soft soil regions generally follow floodplain boundaries, those bridges that cross water courses are considered vulnerable. Key factors in the degree of vulnerability are the facility's age and type of construction and soil classification at the bridge support structure, which indicate the standards to which the facility was built.

Water and Sewer Infrastructure
Water and sewer infrastructure would likely suffer considerable damage in the event of an earthquake.

This factor is difficult to analyze based on the amount of infrastructure and because water and sewer 1541 Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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infrastructure are usually linear easements, which are difficult to thoroughly assess in Hazus. Without further analysis of individual system components, it should be assumed that these systems are exposed to breakage and failure . Distribution systems with older brittle pipes are vulnerable to shaking and liquefaction in particular. Water and sewer restoration generally takes longer than other critical infrastructure.

ENVIRONMENT
The environmental vulnerability from earthquakes would be an expansion of what was discussed under environmental exposure in Section 8.4.4. Secondary hazards will likely have some of the most damaging effects on the environment. Earthquake-induced landslides in landslide-prone areas can significantly damage surrounding habitat. It is also possible for streams to be rerouted after an earthquake. Rerouting can change the water quality, possibly damaging habitat and feeding areas. There is a possibility that streams fed by groundwater wells will dry up because of changes in underlying geology.

ECONOMIC IMPACT
Earthquake events can severely disrupt the economy of the affected area. Economic impact will be largely associated with the disruption of power, gas, telecommunication, water, and wastewater services caused by an earthquake event. In general, significant events may cause damage to land, buildings, transportation infrastructure, and businesses. With an event of such significance, economic recovery could take years, depending on available recovery funds.

The total economic impact of a major earthquake is likely to spread well beyond the impacted area, especially in a population center like the Santa Clara County OA. This is often referred to the "ripple effect" (National Academies of Science, Engineering and Medicine, 2017). The United States has a highly developed, specialized, interdependent, money economy. While those features make the economy productive and resilient, they also mean that a large magnitude earthquake will not be just a regional event. It has the potential to impact the national economy. An earthquake can result in three kinds of national economic damage:
• Disruptions to supply lines
• Shocks to financial markets
• Drain on the insurance system.

Various sectors of an economy would be impacted differently. For example; tourism would likely be impacted over a long term while the impacted area recovers. The retail sector would likely recover quickly to support recovery, and the construction sector would eventually experience growth.

FUTURE TRENDS IN DEVELOPMENT
Unincorporated Santa Clara County and the development departments in participating jurisdictions will strictly enforce all seismic building codes and design standards to prevent loss of life and property caused by earthquake. Public education, cooperation with the development community, and individual preparedness are essential as the OA welcomes thousands of new residents and hundreds of new businesses to each year.

Land use planning is directed by general plans adopted under California's General Planning Law.

Municipal planning partners are encouraged to establish General Plans with policies directing land use and dealing with issues of geologic and seismic safety. These plans provide the capability at the local municipal level to protect future development from the impacts of earthquakes. All planning partners reviewed their general plans under the capabilitY assessments performed for this effort. Deficiencies 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1155

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identified by these reviews can be identified as mitigation actions to increase the capability to deal with future trends in development.

Since all of the Santa Clara County Operational Area is located within an earthquake hazard zone, all future development will, to some extent, be exposed to the earthquake hazard.

SCENARIO
With the abundance of fault exposure in the Bay Area, the potential scenarios for earthquake activity are many. According to the USGS, there is a 72-percent probability by 2043 of one or more earthquakes in the San Francisco Bay region with a magnitude of 6.7 or greater. An earthquake does not have to occur within the OA to have a significant impact on the people, property and economy of the OA.

Any seismic activity of 6.0 or greater on faults within the OA would have significant impacts throughout the OA. Potential warning systems could give up to approximately 40 seconds notice that strong earthquake shaking is about to occur. This would not provide adequate time for preparation.

Earthquakes of this magnitude or higher would lead to massive structural failure of property on NEHRP C, D, E, and F soils. Levees and revetments built on these poor soils would likely fail, representing a loss of critical infrastructure. These events could cause secondary hazards, including landslides and mudslides that would further damage structures. River valley hydraulic-fill sediment areas are also vulnerable to slope failure~ often as a result of loss of cohesion in clay-rich soils. Soil liquefaction would occur in water-saturated sands, silts or gravelly soils.

ISSUES
Important issues associated with an earthquake include the following:
• More quantitative information is needed on the exposure and performance of soft-story construction within the OA.
• Approximately 29 percent of the OA's building stock was built prior to 1975, when seismic provisions became uniformly applied through building code applications. • Based on the modeling of critical facility performance performed for this plan, a portion of facilities in the OA is expected to have complete or extensive damage from scenario events.

These facilities are prime targets for structural retrofits. • Critical facility owners should be encouraged to create or enhance continuity of operations plans using the information on risk and vulnerability contained in this plan. • Geotechnical standards should be established that take into account the probable impacts from earthquakes in the design and construction of new or enhanced facilities. • There are a large number of high risk dams within the OA. Dam failure warning and evacuation plans and procedures should be reviewed and updated to reflect the dams' risk potential associated with earthquake activity in the region. • Earthquakes could trigger other natural hazard events such as liquefaction, dam failures and landslides, and fire which could severely impact the OA. • A worst-case scenario would be the occurrence of a large seismic event during a flood or high­ water event. Levee failures would happen at multiple locations, increasing the impacts of the individual events.
• Citizens are expected to be self-sufficient up to 3 days after a major earthquake without government response agencies, utilities, private-sector services, and infrastructure components. Education programs are currently in place to facilitate development of 156 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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individual, family, neighborhood, and business earthquake preparedness. Government alone can never make this region fully prepared. It takes individuals, families, and communities working in concert with one another to truly be prepared for disaster. • After a major seismic event, the Santa Clara County Operational Area is likely to experience disruptions in the flow of goods and services resulting from the destruction of major transportation infrastructure across the broader region. • The Santa Clara County OA is home to multiple tech centers that provide goods and services to the nation and world. A major earthquake in the region would disrupt these service providers and severely impact the economic and functional stability of the region and potentially the country.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1157 FLOOD

GENERAL BACKGROUND

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A floodplain is the area adjacent to a river, creek or lake that becomes inundated during a flood.

Floodplains may be broad, as when a river crosses an extensive flat landscape, or narrow, as when a river is confined in a canyon.

When floodwaters recede after a flood event, they leave behind layers of rock and mud . These gradually build up to create a new floor of the floodplain. Floodplains generally contain unconsolidated sediments (accumulations of sand, gravel, loam, silt, and/or clay), often extending below the bed of the stream. These sediments provide a natural
filtering system, with water percolating back into the ground and replenishing groundwater. These are often important aquifers, the water drawn from them being filtered
compared to the water in the stream. Fertile, flat reclaimed floodplain lands are commonly used for agriculture,
commerce and residential development.

Connections between a river and its floodplain are most apparent during and after major flood events. These areas form a complex physical and biological system that not only supports a variety of natural resources but also provides natural flood and erosion control. When a river is separated from its floodplain with levees and other flood control facilities, natural, built-in benefits can be lost, altered, or significantly reduced.

MEASURING FLOODS AND FLOODPLAINS
The frequency and severity of flooding are measured using a discharge probability, which is the probability that a certain river discharge (flow) level will be equaled or exceeded in a given year. Flood studies use historical records to determine the probability of occurrence for the different discharge

DEFINITIONS
Flood-The inundation of normally dry land
resulting from the rising and overflowing of a
body of water.

Floodplain-The land area along the sides of
a river that becomes inundated with water
during a flood.
1-Percent-Annual-Chance (1 ~O-Year)
Floodplain-The area flooded by the flood that
has a 1-percent chance of being equaled or
exceeded in a given year. The 1-percent­
annual-chance flood is the standard used by
most federal and state agencies.

O.2-Percent-Annual-Chance (500-Year)
Floodplain-The area flooded by the flood that
has a O.2-percent chance of being equaled or
exceeded in a given year.

Regulatory Floodway-Channel of a river or
other water course and adjacent land areas that
must be reserved for discharge of the base
flood without cumulatively increasing water
surface elevation more than a designated
height. Communities must regulate
development in these floodways to ensure no
Increases in upstream flood elevations.

Return Period-The average number of years
b"etween occurrences of a hazard (equal to the
I n~eTSe ,(if the annual likelihood of occurrence).

RIparian Zone-The area along the banks of a
natural waterCElurse.
levels. The flood frequency equals 100 divided by the discharge probability. For example, the 100-year discharge has a I-percent chance of being equaled or exceeded in any given year. The "annual flood" is the greatest flood event expected to occur in a typical year. These measurements reflect statistical averages only; it is possible for two or more floods with a 100-year or higher recurrence interval to occur in a short time period. The same flood can have different recurrence intervals at different points on a river.

The extent of flooding associated with a I-percent annual probability of occurrence (the base flood or 100-year flood) is used as the regulatory boundary by many agencies. Also referred to as the special flood hazard area (SFHA), this boundary is a convenient tool for assessing vulnerability and risk in flood-prone communities. Many communities have maps that show the extent and likely depth of flooding for the 158 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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base flood. Corresponding water-surface elevations describe the elevation of water that will result from a given discharge level, which is one of the most important factors used in estimating flood damage.

FLOODPLAIN ECOSYSTEMS
Floodplains can support ecosystems that are rich in plant and animal species. A floodplain can contain 100 or even 1,000 times as many species as a river. Wetting of the floodplain soil releases an immediate surge of nutrients: those left over from the last flood, and those that result from the rapid decomposition of organic matter that has accumulated since then. Microscopic organisms thrive and larger species enter a rapid breeding cycle. Opportunistic feeders (particularly birds) move in to take advantage. The production of nutrients peaks and falls away quickly, but the surge of new growth endures for some time. This makes floodplains valuable for agriculture. Species growing in floodplains are markedly different from those that grow outside floodplains. For instance, riparian trees (trees that grow in floodplains) tend to be very tolerant of root disturbance and very quick-growing compared to non­ riparian trees .

EFFECTS OF HUMAN ACTIVITIES
Because they border water bodies, floodplains have historically been popular sites to establish settlements. Human activities tend to concentrate in floodplains for a number of reasons : water is readily available; land is fertile and suitable for farming; transportation by water is easily accessible; and land is flatter and easier to develop. But human activity in floodplains frequently interferes with the natural function of floodplains. It can affect the distribution and timing of drainage, thereby increasing flood problems. Human development can create local flooding problems by altering or confining drainage channels. This increases flood potential in two ways: it reduces the stream's capacity to contain flows, and it increases flow rates or velocities downstream during all stages of a flood event.

FEDERAL FLOOD PROGRAMS
National Flood Insurance Program
The NFIP makes federally backed flood insurance available to homeowners, renters, and business owners in participating communities. For most participating communities, FEMA has prepared a detailed Flood Insurance Study. The study presents water surface elevations for floods of various magnitudes, including the I-percent annual chance (lOO-year) flood and the 0.2-percent annual chance (SOD-year) flood. Base flood elevations and the boundaries of the 100-and SOD-year floodplains are shown on Flood Insurance Rate Maps (FIRMs), which are the principle tool for identifying the extent and location of the flood hazard . FIRMs are the most detailed and consistent data source available, and for many communities they represent the minimum area of oversight under their floodplain management program. In recent years, FIRMs have been digitized and renamed Digital Flood Insurance Rate Maps (DFIRM). This change renders the documents more accessible to residents, local governments and stakeholders.

Participants in the NFIP must, at a minimum, regulate development in floodplain areas in accordance with NFIP criteria. Before issuing a permit to build in a floodplain, participating jurisdictions must ensure that three criteria are met:
• New buildings and those undergoing substantial improvements must, at a minimum, be elevated to protect against damage by the 100-year flood. • New floodplain development must not aggravate existing flood problems or increase damage to other properties.
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• New floodplain development must exercise a reasonable and prudent effort to reduce its adverse impacts on threatened salmonid species.

Table 9-llists each participating municipal jurisdiction ' s date of entrance into the NFIP and the effective date for its current FIRM. Structures permitted or built in the OA before these dates are called" pre-FIRM" structures, and structures built afterwards are called "post-FIRM." The insurance rate is different for the two types of structures . Details about participation in the NFIP are further describ ed the individual annexes in Volume 2 of this plan.

TABLE 9-1. NFIP STATUS IN THE OPERATIONAL AREA
Communit NFIP Comm unit # I NFIP Entr Date Current Effective FIRM City of Campbell 060338 06/30/1976 02/19/2014
City of Cupertino 060339 05/01/1980 05/18/2009
City of Gilroy 060340 08/01 /1980 05/18/2009
City of Los Altos 060341 07/16/1980 05/18/09
Los Altos Hills 060342 01/02/1980 05/18/09
Los Gatos 060343 01/17/1979 02/19/2014
City of Milpitas 060344 07/16/1980 02/19/2014
City of Monte Sereno 060345 05/18/2009 ' 02/19/2014
City of Morgan Hill 060346 06/18/1980 05/18/2009
City of Mountain View 060347 08/15/1980 05/18/2009
City of Palo Alto 060348 09/19/1984 10/16/2012
City of San Jose 060349 08/02/1982 02/19/2014
City of Santa Clara 060350 07/16/1980 02/19/2014
City of Saratoga 060351 01/17/1979 10211 9/2014
City of Sunnyvale 060352 05/15/1978 0511 812009
Unincorporated County 060337 08/02/1982 0211912014
All participating planning partners are currently in good standing with the provisions of the NFIP .

Compliance is monitored by FEMA regional staff and by the California Department of Water Resources under a contract with FEMA. Maintaining compliance under the NFIP is an important component of flood risk reduction. All planning partners that participate in the NFIP have identified actions to maintain compliance and good standing .

FEMA Regulatory Flood Zones
FEMA defines flood hazard areas as areas shown on a map to be inundated by a flood of a given magnitude. These areas are determined via statistical analyses of records of river flow, storm tides, and rainfall; information obtained through consultation with the community; floodplain topographic surveys; and hydrologic and hydraulic analyses. Flood hazard areas are delineated on DFIRMs, which are official maps of a community on which the Federal Insurance and Mitigation Administration has delineated both SFHAs and risk premium zones applicable to the community. In addition to this, DFIRMS identify locations of specific properties in relation to SFHAs; base flood elevations (I-percent annual chance) at specific sites; magnitudes of flood within specific areas ; undeveloped coastal barriers where flood insurance is not available; and regulatory floodways and floodplain boundaries (I-percent and O.2-percent annual chance floodplain boundaries).

Land area covered by floodwaters of the base flood is the SFHA on a DFIRM-an area where NFIP floodplain management regulations must be enforced, and where mandatory purchase of flood 160 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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insurance applies. This regulatory boundary is a convenient tool for assessing vulnerability and risk in flood-prone communities, because many communities have maps showing the extent of the base flood and likely dep~s that will occur.

The I-percent annual chance flood is also referred to as the base flood elevation. As noted earlier, the NFIP defines the base flood elevation as the elevation of a base flood event or a flood which has a 1- percent chance of occurring in any given year. The base flood elevation is the exact elevation of water that will result from a given discharge level, one of the most important factors in estimating potential damage within a given area. A structure within a I-percent annual chance floodplain has a 26-percent chance of undergoing flood damage during the term of a 3D-year mortgage. The I-percent annual chance flood is a regulatory standard adopted by federal agencies and most states to administer floodplain management programs. The I-percent annual chance flood is used by the NFIP as the basis for insurance requirements nationwide. DFIRMs also depict O.2-percent annual chance flood designations (SOD-year events).

DFIRM, FIRMs, and other flood hazard information can be used to identify the expected spatial extent of flooding from a 1-percent and O.2-percent annual chance event. DFIRMS and FIRMS depict SFHAs­ those areas subject to inundation from the I-percent annual chance. Those areas are defined as follows:
• Zones AI-3D and AE: SFHAs that are subject to inundation by the base flood, determined using detailed hydraulic analysis. Base Flood Elevations are shown within these zones. • Zone A (Also known as Unnumbered A-zones): SFHAs where no Base Flood Elevations or depths are shown because detailed hydraulic analyses have not been performed. • Zone AO: SFHAs subject to inundation by types of shallow flooding where average depths are between 1 and 3 feet. These are normally areas prone to shallow sheet flow flooding on sloping terrain.
• Zone VE, VI-3~: SFHAs along coasts that are subject to inundation by the base flood with additional hazards due to waves with heights of 3 fe.et or greater. Base Flood Elevations derived from detailed hydraulic analysis are shown within these zones. • Zone B and X (shaded): Zones where the land elevation as been determined to be above the Base Flood Elevation, but below the SOD-year flood elevation. These zones are not SFHAs. • Zones C and X (unshaded): Zones where the land elevation has been determined to be above both the Base Flood Elevation and the SOD-year flood elevation. These zones are not SFHAs.

Bay-adjacent SFHAs are of concern to the Santa Clara County Operational Area, particularly where land is at or slightly above sea level.

In California, the DWR is the coordinating agency for floodplain management. The DWR works with FEMA and local governments by providing grants and technical assistance, evaluating community floodplain management programs, reviewing local floodplain ordinances, participating in statewide flood hazard mitigation planning, and facilitating annual statewide workshops. Compliance is monitored by FEMA regional staff and by the DWR.

The Community Rating System
The CRS is a voluntary program within the NFIP that encourages floodplain management activities that exceed the minimum NFIP requirements. Flood insurance premiums are discounted to reflect the reduced flood risk resulting from community actions meeting the following three goals of the CRS:
• Reduce flood losses.
• Facilitate accurate insurance rating.
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For participating communities, flood insurance premium rates are discounted in increments of 5 percent.

For example, a Class 1 community would receive a 45 percent premium discount, and a Class 9 community would receive a 5 percent disc:ount. (Class 10 communities are those that do not participate in the CRS; they receive no discount.) The discount partially depends on location of the property.

Properties outside the SFHA receive smaller discounts: a 10-percent discount if the community is at Class 1 to 6 and a 5-percent discount if the community is at Class 7 to 9.

The CRS classes for local communities are based on 18 creditable activities in the following categories:
• Public information.
• Mapping and regulations.
• Flood damage reduction.
• Flood preparedness.

Figure 9-1 shows the nationwide number of CRS communities by class as of October 2016, when there were 1,391 communities receiving flood insurance premium discounts under the CRS program.

Source: FEMA, 2016
500 475
400
III
Q)
350 :w '2
~
E
E 300 0
0 .... 0
222 ... 217 Q)
.Q
E 200
~
z
116
100
1 4 3 3
0 1 2 3 4 5 6 7 8 9
CRS Class
FIGURE 9-1. CRS COMMUNITIES BY CLASS NATIONWIDE AS OF OCTOBER 2016 CRS activities can help to save lives and reduce property damage. Communities participating in the CRS represent a significant portion of the nation's flood risk; over 66 percent of the NFIP's policy base is located in these communities. Communities receiving premium discounts through the CRS range from 162 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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small to large and represent a broad mixture of flood risks, including both coastal and riverine flood risks.

Current CRS ratings are detailed in each jurisdiction's annex and in Table 9-2. Many of the mitigation actions identified in planning partners' individual annexes for this plan are creditable activities under the CRS program. Therefore, successful implementation of this plan offers the potential to enhance the CRS classification.

TABLE 9-2. CRS COMMUNITY STATUS IN THE OA
C t NFIP I CRS Entry Current CRS % Premium Discount , Total Premium ommunl y Commun it # Date Classification SFHA/non-SFHA Savin S 20 14 Cupertino 060339 , 10101/2005 7 15/5 $6,537
Gilroy 060340 05/0112007 8 10/5 $23,722 --
Los Altos 060341 10/01/1991 8 10/5 $10,465
Milpitas 060344 10/01 /1991 7 15/5 $329}49
Morgan Hill 060346 05/01 /2003 7 15/5 $51 ,026
Mountain View 060347 05/01/2002 8 10/5 $53,181
Palo Alto 1060348 10/01/1991 7 15/5 $713,103
San Jose 060349 10/01 /1991 7 15/5 $1,234,021
Santa Clara (city) 060350 05/01 /2002 8 10/5 $94,810
060352 10/01/1998 7 15/5 $170,009
$2,686,623
Source: FEMA, 2016

HAZARD PROFILE
The following information is extracted from the Santa Clara County Flood Insurance Study (FEMA,2014):
• The mountains and foothills in northern Santa Clara County are the sources of the watercourses that flow through the north portion of the OA. Near San Jose, the major waterways include Los Gatos, Guadalupe, and Alamitos Creeks flowing out of the Santa Cruz Mountains; Coyote Creek and a host of tributaries, including Upper Penitencia and Silver Creeks, flowing out of the Diablo Range; and Fisher Creek with headwaters on the western side of the Coyote Creek Valley. The 75-mile-Iong Coyote Creek is the primary natural drainage facility for the eastern side of the Santa Clara Valley. • Permanente and Stevens Creeks, which flow north through the OA near Mountain View, are the primary runoff drainage channels in that area. In addition to providing flood control, these creek beds provide gravel lenses that penetrate the impervious underground clay layers.

These lenses allow rain runoff to percolate down to replenish the underground water supply. • The principal watercourses in the south portion of the OA are Llagas, Uvas, and Coyote Creeks. Edmundson (Little Llagas), Church, Center, Tennant, Maple, and Foothill Creeks also flow through the area. The area is unusual in that creeks originate in both the Diablo Range, to the east, and the Santa Cruz Mountains, to the west. Waters originating in the area are conveyed to Monterey Bay via the Pajaro River.
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• Drainage-ways in the OA are a combination of natural channels (creek beds) and channels altered by human activity.
• Drainage patterns in the OA have been altered by urbanization, and the runoff, which has increased, is a greater flood threat than in previous years. The construction of water­ conservation flood retention facilities has also altered the drainage pattern. • A variety of conditions cause flooding in the Santa Clara County OA. In smaller drainage basins, flooding is usually the result of intense storms. In larger basins, flooding results from storms of long duration. Shallow overland flooding often occurs due to the small capacity of the creeks.

TYPES OF FLOOD-RELATED HAZARDS
Flooding in the Santa Clara County OA typically occurs during the rainy winter season. Four types of flooding primarily affect the County: stormwater runoff, riverine, flash floods, and tidal floods.

Stormwater Runoff Floods
Stormwater flooding is a result of local drainage issues and high groundwater levels. Locally, heavy precipitation, especially during high lunar tide events, may induce flooding within areas other than delineated floodplains or along recognizable channels due to presence of storm system outfalls inadequate to provide gravity drainage into the adjacent body of water. If local conditions cannot accommodate intense precipitation through a combination of infiltration and surface runoff, water may accumulate and cause flooding problems. Flooding issues of this nature generally occur within areas with flat gradients, and generally increase with urbanization, which speeds accumulation of floodwaters because of impervious areas. Shallow street flooding can occur unless channels have been improved to account for increased flows (FEMA, 1997). Numerous areas within the County undergo stormwater flooding that contributes to street and structure inundation.

Urban drainage flooding is caused by increased water runoff due to urban development and drainage systems. Drainage systems are designed to remove surface water from developed areas as quickly as possible to prevent localized flooding on streets and within other urban areas. These systems utilize a closed conveyance system that channels water away from an urban area to surrounding streams, and bypasses natural processes of water filtration through the ground, containment, and evaporation of excess water. Because drainage systems reduce the amount of time surface water takes to reach surrounding streams, flooding in those streams can occur more quickly and reach greater depths than prior to development within that area (FEMA, 2008).

Riverine Floods
Riverine flooding is overbank flooding of rivers and streams. Natural processes of riverine flooding add sediment and nutrients to fertile floodplain areas. Flooding in large river systems typically results from large-scale weather systems that generate prolonged rainfall over a wide geographic area, causing flooding in hundreds of smaller streams, which then drain into the major rivers. Shallow area flooding is a special type of riverine flooding. FEMA defines shallow flood hazards as areas inundated by the 100- year flood with flood depths of only 1 to 3 feet. These areas are generally flooded by low-velocity sheet flows of water. Two types of flood hazards are generally associated with riverine flooding:
• Inundation - Inundation occurs when floodwater is present and debris flows through an area not normally covered by water. These events cause minor to severe damage, depending on velocity and depth of flows, duration of the flood event, quantity of logs and other debris 164 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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carried by the flows, and amount and type of development and personal property along the floodwater's path.
• Channel Migration - Erosion of banks and soils worn away by flowing water, combined with sediment deposition, causes migration or lateral movement of a river channel across a floodplain. A channel can also abruptly change location (termed "avulsion"); a shift in channel location over a large distance can occur within as short a time as one flood event.

Natural stream channels in rural parts of the Santa Clara County OA typically can accommodate average rainfall amounts and mild storm systems; however, severe floods occur in years of abnormally high rainfall or unusually severe storms. During those periods of severe floods, high-velocity floodwaters carry debris over long distances, block stream channels, and create severe localized flooding.

Flash Floods
The National Weather Service defines a flash flood as a rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level.

Such floods generally begin within 6 hours of the rain event that causes them. Ongoing flooding can intensify to flash flooding in cases where intense rainfall results in a rapid surge of rising flood waters (NWS, 2009).

Flash floods can tear out trees, undermine buildings and bridges, and scour new channels. In urban areas, flash flooding is an increasingly serious problem due to removal of vegetation and replacement of ground cover with impermeable surfaces such as roads, driveways, and parking lots. The greatest risk from flash floods is occurrence with little to no warning. Major factors in predicting potential damage are intensity and duration of rainfall, and steepness of watershed and streams.

Tidal Floods
Tidal floods are characterized by inundation of normally dry lands by bay waters, often caused by extreme high tide events that result in shallow flooding of low-lying coastal areas. Colloquially known as "King Tides," extreme high level tide events are the highest predicted high tide events of the year at a coastal location. These tides exceed the highest water level reached at high tide on an average day and normally occur once or twice per year. King Tide events are the leading cause of flooding by bay waters.

Tidal flooding is becoming increaSingly exacerbated by sea level rise as a result of climate change or tectonic activity (NOAA, no date). Average daily water levels are rising along with the oceans. As a result, high tides are reaching higher and extending further inland than in the past. Additional information regarding the impacts and exposure of the OA to sea level rise is presented in Chapter O.

PRINCIPAL FLOODING SOURCES
FEMA's Flood Insurance Study for Santa Clara County assessed over 50 creeks, channels, and water bodies, including the following principal flooding sources (FEMA, 2014):
• Adobe Creek • Guadalupe Slough • San Tomas Aquino
• Alamitos Creek • Hale Creek Creek Reach 2
• Alviso Slough • Lions Creek • Saratoga Creek
• Arastradero • Llagas Creek • Silver Creek
Creek • Llagas Overbank • Smith Creek
• Arroyo Calero • Los Gatos Creek • South Babb Creek
• Barron Creek • Lower Penitencia • South Morey Creek
• Berryessa Creek Creek • Stevens Creek
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• Calabazas Creek • Matadero Creek • Sunnyvale East
• Canoas Creek • Miguelita Creek Channel
• Concepcion Drain • Miller Slough • Sunnyvale West
• Coyote Creek • North Morey Creek Channel
• Daves Creek • Permanente Creek • Thompson Creek
• East Little Llagas • Permanente • Upper Penitencia
Creek Diversion Creek
• East Penitencia • Purissima Creek • Upper Penitencia
Creek • Quimby Creek Creek Reach 2
• Evergreen Creek • Ronan Channel • Upper Penitencia
• Fisher Creek • Ross Creek Creek Reach 2
• Fisher Creek • Ruby Creek Overflow
Overbank • San Francisco Bay • Uvas Creek
• Flint Creek • San Francisquito • West Branch Llagas
• Fowler Creek Creek Creek
• Guadalupe River • San Joaquin River • West Little Llagas • Santa Teresa Creek Creek
• San Tomas Aquino • Wildcat Creek
Creek
Investigation of Santa Clara County's vulnerability to flooding can also include assessments of watersheds. Every watershed has unique qualities that affect its response to rainfall. The Santa Clara County OA contains five watersheds (SCVWD, 2017):
• Coyote Watershed is the OA's largest watershed, with 322 square miles. It contains Coyote Creek, which is the longest creek in the county.
• Guadalupe Watershed drains the Guadalupe River and its tributaries through downtown San Jose.
• Lower Peninsula Watershed is a small-creek watershed that feeds tidal wetlands along the San Francisco Bay's southwest shoreline.
• Uvas-Llagas Watershed is mainly agricultural land and natural areas. This is the only watershed in the county where waterways flow southward. • West Valley Watershed is the smallest watershed in the county, covering 85 square miles of numerous small creeks.

PAST EVENTS
Based on NOAA's National Centers for Environmental Information and the ABAG 2010 Plan, 23 flood events in the OA were recorded between 1950 and 2016, as summarized in Table 9-3. These events include flash floods, winter storm flooding, urban and small stream flooding, and flooding from heavy multi-day rain events. Since 1954, 13 presidential-declared flood events in the OA have caused in excess of $4.468 billion in property damage throughout the region.

According to the USDA's Risk Management Agency, Santa Clara County received $8,200,676 in payments for insured crop losses on 2,710 affected acres as a result of excessive moisture and flood events between 2003 and 2016. Table 9-4 summarizes these payments. The highest damaging year was 2016. 166 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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LOCATION
Flooding that has occurred in portions of the OA has been extensively documented by gage records, high water marks, damage surveys and personal accounts. This documentation was the basis for the 2014 FIRMs generated by FEMA for the Santa Clara County OA. The 2014 current effective Flood Insurance Study is the sole source of data used in this risk assessment to map the extent and location of the flood hazard, as shown in
Figure 9-2. MAPPED FLOOD HAZARD AREAS IN THE OPERATIONAL AREA

FREQUENCY
Figure 9·2.

Mapped Flood Hazard
Areas in the
Operational Area
1 % Annual Chance (100-Year)
Flood Zone
_ 0.2% Annual Chance (500-
- Year) Flood Zone
L I So nta Clara County Boundary
o County Boundarie s
Water Bodies & Channels
Flood hazard on.as as depicted on
Err.ctlve FEMA Oigltallnsurance Rate
Maps (DFIRM)
~TETRATECH
16 Map Da'" Sourcos: Sanla Cllra couney.

Miles CaITr.ns. FEMA. USDA
Recurrence intervals and average annual numbers of events in the Santa Clara County OA were calculated based on data from 1996 to 2016 in NOAA's Storm Events Database. Santa Clara County has experienced nine significant events since 1996 classified as "flood" in the database. Smaller floods may occur more frequently and be categorized as a different event type, typically "flash flood" or "winter storm." Based on these data, floods have a 52 percent chance of occurring in any given year, flash floods have a 38 percent chance, and winter storms have a 10 percent chance. Total estimated percent chance of occurrence for any type of flood in a given year is 100 percent, meaning that flooding will likely continue to be an annual hazard.
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Additionally, 45 flood-related federally declared disasters or emergencies have occurred in California since 1954 (all 45 events were non-tsunami or hurricane-related flood events). This equates to a major, non-tsunami or hurricane-related flood event impacting the state every 1.37 years on average.

TABLE 9-3. HISTORY OF FLOOD EVENTS
, Declaration I Date 1# Type of event Estimated Damage
2/5/1954 15 Flood & Erosion Not available
12123/1955 47 Flood Coyote Creek, Stevens Creek, Matadero Creek, San I Francisquito Creek, and Guadalupe River flooded
Penitencia Creek, Guadalupe River, San Tomas Aquinas
4/4/1958 82 Heavy Rainstorms and Flood Creek, Stevens Creek, Permanente Creek, Matadero Creek, and San Francisquito Creek flooded. $20 million, plus $4 million agricultural damage
3/6/1962 122 Floods Not available
10124/1962 138 Severe Storms and Flooding $4 million in regional flooding 2/2511963 145 Severe Storms, Heavy Rains and Flooding Not available 1/16/1973 N/A . Severe Storms and Flooding $86,207 in damage 1/7/1982 651 Severe Storms, Flood, Mudslides and High $273 million, 256 homes and 41 businesses destroyed; Tide ' 6,259 homes and 1,276 businesses damaged.
2/9/1983 677 Coastal Storms, Floods, Slides and Tornadoes $523 million 2/21/1986 758 Severe Storms and Flooding $407 million; 1,382 homes and 185 businesses destroyed; 12,447 homes and 967 businesses damaged.
2/11-14/1992 N/A Severe Storms and Flooding $20,000 in damage 1/13/1993 N/A Severe Storms and Flooding $112,000 in damage 1/10/1995 1044 Severe Winter Storms, Flooding, Landslides, $741 million total; 11 deaths Mud Flows 3/12/1995 1046 Severe Winter Storms, Flooding Landslides, Approx. $1.1 billion total; damage to homes: major 1,322; Mud Flow minor 2,299; destroyed 267.
1/4/1997 1155 Severe Storms, Flooding, Mud and Landslides $1.8 billion total; 23,000 homes; 2,000 businesses damaged or destroyed.
2/9/1998 1203 . Severe Winter Storms and Flooding $550 million; 17 deaths 2/13/2000 N/A Flash Flood Mainly on Coyote Creek
10/13/2009 N/A Heavy Rain and Flooding $400,000
1/18-20/2010 N/A Heavy Rain and Flooding Localized flooding, roads closed, damage estimate not available.
12/23/2012 N/A Heavy Rain and Tornado Localized flooding, levee overtopped in East Palo Alto. 2/2812014 N/A Heavy Rain and Flooding Flooding of urban areas, small streams and creeks, and a few localized mud and rockslides.
12/11/2014 N/A Heavy Rain and Flooding Flooding and mudslides 2/0612015 N/A Heavy Rain and Flooding Multiple off ramps from 1-280 flooded. 2/14/2017 4301 S W· t St FI d' d M d I'd 34 of 57 CA Counties declared for flooding events that evere In er orms, 00 lng, an u s I es. occurred from Janua~ 3 to Janua~ 12, 2017 N/A = Not Applicable
Sources: NOAA, 2017 and ABAG, 2010
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TABLE 9-4. CROP INSURANCE CLAIMS PAID FROM EXCESSIVE MOISTURE AND FLOOD, 2003-2016 Cro Year Commo dit Acres Affected Indemmt Amount
2003 I None None None
2004 None None None
2005 All Other Crops 79 $13,144
2006 All Other Crops 83 $6,937
2007 None None None
2008 None None None
2009 None None None
2010 None None None
2011 Walnuts, Cherries, Processing Apricots 910 2,706,413 2012 Cherries 239 $113,052
2013 None None None
2014 Cherries 18 $29,015
2015 Cherries, Processing Apricots, All Other Crops 322 1$1,053,095 2016 Cherries, Processing Apricots 1,059 $4,279,020
Total 2,710 $8,200,676
Source: USDA, 2016
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16 Miles
Figure 9·2.

Mapped Flood Hazard
Areas in the
Operational Area
1% Annual Chance (1 DO-Year)
Flood Zone
_ 0.2% Annual Chance (500-
- Year) Rood Zone
CJ Santa Clara County Boundary
CJ County Boundaries
Water Bodies & Channels
Flood hazard ar.as al depicted on
Elhcliv. FEMA Dlgltallnsuronco "at.

Maps (DFIRM)
~TETRATECH
Map Data SOurc .. : Santa Clara county.

Camans. FEMA. USDA
FIGURE 9-2. MAPPED FLOOD HAZARD AREAS IN THE OPERATIONAL AREA 170 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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SEVERITY
The principal factors affecting flood damage are flood depth and velocity . The deeper and faster flood flows become, the more damage they can cause. ShaUowflooding with high velocities can cause as much damag e as deep flooding with slow velocity. This is especially true when a channel migrates over a broad floodplain, redir ecting high velocity flows and transporting debris and sediment.

Although jurisdictions can implement mitigation and take preventative actions to significantly reduce severity and threat of flood events , some type of residual risk will always exist (i.e., risk of a hazard event occurring despite technical and scientific measures applied to reduce/prevent it). Threats associated with residual risk could include failure of a reservoir, a dam breach, or other infrastructure failure, or a severe flood event that exceeds flood design standards or drainage capacity .

Flood severity is often evaluated by examining peak discharges; Table 9-Slists peak flows used by FEMA to map the floodplains of the OA.

TABLE 9-5. SUMMARY OF PEAK DISCHARGES WITHIN THE OA
. Dischar~ cubiC feeUsecond Flooding Source and Location -10~- '50 Y 10~0 Y "-500 Y - ear - ear - ear - ear

ADOBE CREEK
Above Railroad (At EI Camino Real) 1,350 2,500 2,7008 2,7008 At East Charleston Road 11,4008 1,4008 1,4008 1,4008
At East Meadow Drive 1,350 1,350 1,350 1,350
At Edith Road 1,000 1,830 2,140 2,700
At EI Monte Avenue 690 1,340 i1,700 2,370
At corporate limits 890 1,650 ;1,920 2,400
At Foothill Expressway 1,070 2,120 2,320 2,690
At Middlefield Road 1,0208 1,0208 1,0208 1,0208
At Moody Road 590 1,150 ,1,430 1,930
At Old Altos Road 960 1,760 2,050 2,490
At Pine Lane 1,110 2,150 Q,360 2,730
At Railroad 1,350 1,4508 1,4508 1,4508
At U.S. Highway 101 1,660 1,780 '1,780 1,780
At Van Buren Road 1,060 1,890 '2,220 2,810
Below Alma Street 1,450 1,700 1,700 1,750
Below Purissima Creek 1,040 ' 1,980 2,200 2,510

ALAMITOS CREEK
Downstream of confluence with Arroyo Calero 2,150 5,180 6,750 11,000 Downstream of confluence with Golf Creek 3,530 7,020 8,680 12,700 Downstream of confluence with Greystone Creek -2,940 6,200 7,800 11,800 Downstream of confluence with Randol Creek 2,660 5,800 7,380 11,400 Upstream of confluence with Arroyo Calero 1,430 3,580 4,750 7,900 Upstream of confluence with Guadalupe River 3,630 7,180 8,860 12,900 ALAMITOS CREEK BY·PASS CHANNEL b b 3,250 b
ALAMITOS CREEK OVERFlOW AREA b b 140 b

ARROYO CALERO
Downstream of confluence with Santa Teresa Creek 1,020 1,820 2 , 1~0 3,010 Upstream of confluence with Alamitos Creek 1,180 1,980 2,330 3,110 Upstream of confluence with Santa Teresa Creek ,660 1,120 1,320 1,770

ARASTRADERO CREEK
At Page Mill Road 140 300 360 460
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 171

OFFICE OF EMERGENCY SERVICES

COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
Discharge (cubic feeUsecond)
Flooding Source and Location 10 50 Y 100 Y 1500 Y -year - ear - ear - ear

ARROYO DE LOS COCHES
At confluence with Berryessa Creek b b 1,420 b

BARRON CREEK
At EI Camino Real 270 270 270 270
At Foothill Expressway 176 364 453 640
At Foothill Expressway 320 630 760 1,100
At Laguna Avenue 180b 180b 180b 180b
At Lower Fremont Road 96 208 268 390
At mouth 320 430 430 430
At Ramona Street 320 4308 4308 4308
At Railroad 320 675 675 675
At Upper Fremont Road 32 77 98 143
Downstream of EI Camino Real 270 270 270 270
Upstream of Barron Creek Diversion b b 740 b
Upstream of Fabian Way b b 250 b
Upstream of Laguna Avenue Ib b 1,603 b
Upstream of Railroad 320 820 920 1,080

BERRYESSA CREEK
At confluence with Calera Creek Ib b 3,6008 b
At confluence with Sierra Creek 1,230 2,250 2,580 1,230 At confluence with Tularcitos Creek b b 2,5008 b
At confluence with Wrigley Ditch b b 2,0008 b
At Morrill Avenue 1,230 1,7001 1,7508 1,230
At Piedmont Road b b 1,600 b
Downstream of confluence with Arroyo De Los Coches b b 2,0008 b Downstream of Montague Expressway 8008 8008 8008 8008

CALABAZAS CREEK
Above Prospect Road b b 1,800 b
Above Railroad and Prospect Creek b b 1,140 b
At Coffin Road 3,000 4,100 4,600 5,800
At EI Camino Real 2,090d 2,290d 2,340d 2,360d
At Grant Road 1,200 1,600 1,800 2,300
At Interstate Highway 280 1,950 2,490 2,700 3,360
At Junipero Serro 2,000 2,700 3,100 3,900
At Kifer Road 2,600 3,600 4,000 5,200
At Lawrence Expressway 2,100 3,000 3,300 4,200
At Rainbow Drive Below La Mar Court 750 1,070 1,310 1,370 Below Miller Avenue 1,670 2,050 2,210 2,670
Below Tantau Avenue/Upstream of Pruneridge Avenue 1,7008 1,9008 1,9508 2,0008 Downstream of confluence with Rodeo Creek 1,170 1,700 1,950 2,610 Downstream of Prospect Road 7501 1,000e 1,180e 1,220e
Downstream of U.S. Highway 101 2,760d 3,200f 4,780f 5,510f Through box culvert at Miller Avenue 1,4008 1,5508 1,6008 1,6008 Upstream of Benton Street 2,100d 2,1708 2,1708 2,2008
Upstream of Kifer Road 2,550d 2,820d 3,000d 3,340d
Upstream of Lawrence Expressway 2,050d 2,310d 2.370d 2.540d 172 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

OFFICE OF EMERGENCY SERVICES

COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
FI d· S d L t' Discharge (cubic feet/second) 00 Ing ource an oca Ion 10- ear 50-Year 100-Year 500-Year Upstream of Pomeroy Avenue 2,190d 2,200d 2,200d 2,200d
Upstream of U.S. Highway 101 2,760d 3,020d 3,20Od 3,550d Upstream of State Highway 237 3,010d 3,420d 5,000d 5,100d

CALERA CREEK
At confluence with Berryessa Creek b b 920 b
Upstream of Interstate Highway 680 b b 850 b

CANOAS CREEK
At Blossom Hill Road 1,320 1,390 1,400 1,420
At Capitol Expressway 1,850 1,910 1,960 2,000
At confluence with Guadalupe River 1,900a 1,950a 1,970a 2,000a At Cottle Road 480 500 510 530
At Santa Teresa Boulevard 780 810 830 850
Upstream of Nightingale Drive 1,990 2,250 2,350 2,500

CONCEPCION DRAINAGE
At Alto Verde Lane 22 - 51 68 102

COYOTE CREEK
At Interstate Highway 280 3,880 10,180 12,630 14,700
At U.S. Geological Survey gage near Edenvale 4,050 10,940 13,670 14,700a At U.S. geological Survey gage near Madrone 4,500 12,000 15,000 24,000 Downstream of Anderson Reservoir 4,500 11,000 15,000 23,500 Downstream of confluence with Berryessa Creek 7,300 10,500 12,800 15,000 Downstream of confluence with Silver Creek 6,200 10,300 12,500 15,000 Downstream of Silver Creek Diversion 4,000 10,680 13,330 14,700 Upstream of confluence with Fisher Creek 4,410 12,010 14,830 16,400a Upstream of confluence with Silver Creek 3,790 9,920 11,400a 11,400a Upstream of Silver Creek Diversion 4,000 10,680 13,330 14,700

DAVES CREEK
At Los Gatos Creek 130 230 270 370

EAST LITTLE LLAGAS CREEK
Approx. 1,500 ft. upstream of Sycamore Ave. b b 2,211 b At confluence of Church Creek b b 5,355 b
At confluence of San Martin Creek b b 3,712 b
At U.S. Highway 101 700 1,200 1,300 1,700
At Tenant Creek confluence b b 2,881 b
Upstream of Seymour Ave 330 430 460 490

EAST PENITENCIA CREEK
Downtown of Trimble Road 280 340a 340a 3408
Upstream of confluence with Lower Penitencia Creek 480 970h 1,080h 1,280h Upstream ofTrimble Road 280 400 450 540

FISHER CREEK
At confluence with Coyote Creek 700a 700a 700a 700a
At Kalan a Avenue 470 960 1,130 1,500
At Miramonte Avenue 300 600 710 930
At Richmond Avenue 450 700 700 700
At Willow Springs Road 270 460 560 810
Downstream of Bailey Avenue 1,000 1,810 2,160 2,950
Upstream of Bailey Avenue 620 900 900 900
Upstream of Railroad 1,260 2,310 2,560 3,530
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 173

OFFICE OF EMERGENCY SERVICES

COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
Discharge (cubic feet/second)
Flooding Source and Location 10 50 Y 1100 Y 1500 Y -year - ear - ear - ear

FISHER CREEK OVERBANK
500 feet downstream of Richmond Avenue 250 630 900 1,540 At Bailey Avenue 220b 680 970 1,670

GUADALUPE RIVER
At Blossom Hill Road 3,500 8,500 11,500 19,000
At Coleman Avenue 7,000 13,5008 15,5008 15,5008
At Hedding Street 7,500 9,8008 9,8008 9,8008
At Hobson Avenue 7,000 11,4008 11,4008 11,4008
At Interstate Highway 280 6,000 7,0008 7,0008 7,0008
At Malone Road 5,600 11,500 11,9008 11,9008
At Railroad 5,800 10,9008 10,9008 10,9008
Downstream of confluence with Canoas Creek 5,500 11 ,000 12,800 12,800 Downstream of confluence with Los Gatos Creek 7,0008 10,0008 10,0008 10,0008 Downstream of confluence with Ross Creek 4,500 9,000 12,500 20,000 Downstream of State Highway 17 7,500 12,0008 13,0008 17,0008 Upstream of confluence with Canoas Creek 4,500 9,500 12,0008 12,0008

HALE CREEK
At Berry Avenue 510 1,020 1,120 1,580
At confluence with Permanente Creek 710 880 900 960
At Cuesta Drive/North Springer Road 595 750 760 810
At Foothill Expressway 460 \970 1,060 1,490
At Interstate Highway 280 101 21 8 284 440
At Rosita Avenue 595 7008 7008 7008
At Summer Hill Avenue 177 370 472 735

LIONS CREEK
Upstream of West Branch Uagas Creek b b 1,840 b

LLAGAS CREEK
At Rucker Avenue 4,900; 9,700; 10,200; 12,700;
At Railroad 2,200 3,900 5,3_09 8,500
Downstream of Buena Vista Creek 5,200 10,400 11,000 11,5008 Downstream of Chesbro Reservoir 900 3,100 3,900 6,000
Downstream of East Little Uagas Creek 5,000 9,800 10,400 12,900 Downstream of Hayes Creek 1,800 3,800 4,800 7,500
Downstream of Leavesley Road 5,200d 5,200d 5,200d 5,200d Downstream of Live Oak Creek 5,500 9,700 9,800 10,300
Downstream of Machado Creek 1,400 3,600 4,500 7,000
Downstream of Panther Creek 5,300 9,7008 9,8008 10,1008 Downstream of Princevalle Drain b b 18,800 b
Downstream of West Branch Uagas Creek b b 17,8Q.o b
Upstream of East Little Uagas Creek 2,500 4,300 5,49.0 8,600 Upstream of Jones Creek b b 18,800 b
Upstream of Panther Creek 5,200 9,4008 9,4008 9,400a

LOS GATOS CREEK
At Leigh Avenue 1,680 6,510 7,440 11,340
At Meridian Avenue 1,770 6,620 7,570 11,500
At Park Road 1,580 6,140 6,990 10,630
174 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

OFFICE OF EMERGENCY SERVICES

COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
I
Discharge (cubic feeVsecond)
Flooding Source and Location 10 50 Y 100 Y 500 Y . ear . ear . ear . ear At State Highway 17 1,540k 6,370
Below Lexington Dam 1,610 5,850
Below Vasona Dam 1,550 6,100
Upstream of confluence with Guadalupe River 2,130 7,000

LOWER PENITENCIA CREEK
At Capitol Avenue 740 1,200
At confluence with Berryessa Creek 2,550 3,700
At Nimitz Freeway 1,7508 3,5008
At Redwood Avenue 850 1,15oi
At South Main Street 7003 1,1201
Downstream of confluence with Berryessa Creek 2,550 2,6008 Downstream of confluence with East Penitencia Creek 800 1,670 Downstream of Trimble Road 320 1,060h

MADRONE CHANNEL
At East Dunne Avenue b b
Upstream of East Little Llagas Creek b b

MAT ADERO CREEK
Above confluence with Arastradero Creek 194 392
Approximately 270 feet upstream of U.S. Highway 101 b b At Alma Street 1,380 2,0008
At corporate limits 402 795
At EI Camino Real 1,100 2,100
At Louis Road 1,380 1,500b
At Middlefield Road 1,380 1,900b
At Railroad b b
At U.S. Highway 101 1,660 1,775
Below confluence with Arastradero Creek 325 660
Downstream of Foothill Expressway b b
Downstream of Park Boulevard b b
Downstream of U.S. Highway 101 b b
Upstream of Railroad 1,220 2,170

MILLER SLOUGH
At U.S. Highway 101 b b

MIDDLE ROAD OVERFLOW AREA
At convergence with Llagas Creek b Ib
At divergence from West Little Llagas Creek b b

NORTH MOREY CREEK
Upstream of Lions Creek b b

PAJARO RIVER
At U.S. Highway 101 b b

PERMANENTE CREEK
At confluence with Hale Creek 780' 1,650'
At EI Camino Real 1,150 1,310
At Railroad 1,270 1,470
Downstream of confluence with Hale Creek 1,0008 1,0008
Downstream of East Charleston Road 1,390n 1,4008
Downstream of Miramonte Avenue 370 760
Downstream of Permanente Road 760 1,260
10/15/17 Santa Clara County Operational Area Mitigation Plan 7,300
6,650
6,950
7,980
1,210
3,700
3,5008
1,15oi
1,12oi
2,6008
2,150
1,510h
600
1,200
506
2,800
2,0008
970
2,280
1,500b
1,500b
2,435
1,775
790
1,900
2,700
3,100
12,520
760
39 658
485
30,500
1,780'
1,310
1,600
1,0008
1,4008
890
1,480
111 ,200
9,630
10,600
11 ,900
1,220
3,700
3,5008
1,15oi
1,12oi
2,6008
2,840
1,620h
b
b
690
b
2,0008
1,300
2,690
1,500b
1,900b
b
1,775
1,030
b
b
b
2,810
b
b
b
b
b
1,980'
1,310
1,600
1;0008
1,4008
1,030
1,960

OFFICE OF EMERGENCY SERVICES

COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
Discharge (cubic feeVsecond)
Flooding Source and Location 10 50 Y 100 Y 500 Y - ear - ear - ear . - ear Downstream of Portland Avenue 1,340 2,050 2,050 2,050
Downstream of U.S. Highway 101 1,350 1,4008 1,4008 1,4008 Upstream of confluence with Hale Creek 440' 840' 980' 1,110' Upstream of Interstate Highway 280 1,250 2,160 2,570 3,480 Upstream of Portland Avenue 1,340 2,220 2,700 3,440
Upstream of Tributary, 700 feet upstream of Highway 280 860 1,460 1,720 2,310 Upstream of U.S. Highway 101 1,350 2,250f 4,OOOf 7,100f

PERMANENTE DIVERSION
At confluence with Stevens Creek 1,230 1,280 1,390 1,550 At Grant Road 1,200 1,2408 1,3408 1,4908
Downstream of Carmel Terrace 1,0758 1,0758 1,0758 1,0758 Downstream of Diversion Structure 1,190 1,610 1,610 1,610

PROSPECT CREEK
Upstream of confluence with Calabazas Creek b b 635 b

PURISSIMA CREEK
At corporate limits 147 320 402 588
At Interstate Highway 280 37 82 104 153
At Viscaino Road 88 182 227 320

SAN FRANCISQUITO CREEK
At Alma Street 4,350 7,050 8,280 9,8508
At U.S. Geological Survey gage 4,050 6,700 7,860 10,500 Downstream of Chaucer Road 4,350 6,0008 6,0008 6,2008
Downstream of Middlefield Road 4,350 6,3508 6,6908 7,4108 Near Pasteur Drive 4,200 6,850 8,070 10,400
Upstream of Middlefield Road 4,350 7,100 8,330 9,8508
SAN FRANCISQUITO CREEK· OVERFLOW
At Chaucer Street b b 563 b
At Middlefield Road b b 752 b
Combined Middlefield/Chaucer Overflows b b 1,080 b

SAN THOMAS AQUINO CREEK
At Cabrillo Avenue 2,560f 2,920f 2,920f 2,920f
At confluence with Saratoga Creek 5,900 8,300 9,100 11,000 At EI Camino Real 3,570 3,610 3,610 3,610
At Homestead Road 3,450f 3,450f 3,450f 3,450f
At Pruneridge Avenue 3,460 3,820f 3,820f 3,820f
At Saratoga and Los Gatos Roads 620 990 1,140 1,480
At Stevens Creek Boulevard 3,300 3,820f 3,820f 3,820'
At U.S. Highway 101 5,900 8,300 9,100 11 ,000
At U.S. Highway 237 5,900 8,300 9,100 11,000
Downstream of Railroad 5,900 8,300 9,100 11 ,000
Upstream of Westmont Avenue 2,000 2,900 3,200 4,0770
Near Bicknell and Quito Roads 670 1,050 1,230 1,580
Near Old Adobe and Quito Roads 730 1,150 1,350 1,720

SARATOGA CREEK
At confluence with San Tomas Aquino Creek 2,700 3 , 7~0 14,100 4, 80~ At EI Camino Road 2,700 3,750 4,190 4,800
At Herriman Avenue 1,550 13,020 ' 3,750 4,630
1761 Page Santa Clara County Operational Area Mitigation Plan 10/15/17

OFFICE OF EMERGENCY SERVICES

COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
. I Discharge (cubic feeVsecond)
Flooding Source and Location 10 50 Y ' 100 Y 500 Y - ear - ear - ear - ear At Homestead Road 12,700 13,750 4,100 4,800
At Kiely Boulevard 2,7.00 3}50 4,100 4,800
At Stevens Creek Boulevard 2,500 3,500 3,900 4,600
At U.S. Geological Survey gage at Springer 1,35.0 2,75.0 3,490 4,45.0 At Railroad 1,76.0 3 , 2~ 0 3,95.0 4,8.0.0
Downstream of Benton Street 2,700 p,750 4,1.0.0 4,8qO
Downstream of Kiely Boulevard 2,70.0 3,750 4,100 4,8.0.0 Downstream of Warburton Avenue 12,700 3,750 4,10.0 4,800

SILVER CREEK
At confluence with Coyote Creek 2,550 2,650 2,670 2,750 At intersection of King and McKee Roads 2,0008 2,.oooa 2,0008 2,000a At Interstate Highway 680 2,210 2,400 2,400 2,400
At Ocala Avenue 1,530 2,.oOOP 2,000P 2,000P
Downstream of confluence with Thompson Creek 2,080 3,200 3,600 4,300 Downstream of Cunningham Avenue 1,420P 2,150P 2,580P 2,600P Downstream of confluence with Miguelita Creek 2,300 2,300 2,300 2,300 Downstream of confluence with North Babb Creek 1,500a 1,5008 1,500a 1,500a Downstream of confluence with South Babb Creek ·1,940 2,600 2,700 2.70.0

SMITH CREEK
At Railroad 200 370 440 610
At Wedgewood Avenue 160 300 350 480
Below Smith Creek Drive 125 23.0 280 390

SOUTH BABB CREEK
At Clayton Road 390 760 890 1,150
At confluence with Silver Creek 200a 200a 200a 200a
Downstream of White Road 390a 39.oa 3908 390a
Upstream of Clayton Road b Ib 890 b
Upstream of Lochner Drive 400 550a 5508 550a
Upstream of White Road 400 570a 570a 570a

SOUTH MOREY CREEK
Upstream of Lions Creek b b 420 ' b

STEVENS CREEK
At Crittenden Lane 2,350g 2,350g 2,350g 2,350g
At Homestead Road 1,110m 4,530 5,570 7,470
At Interstate Highway 280 1,11.om 4,460 5,460 7,310
At Stevens Creek Boulevard 1,110m 4,430m 5,430 7,240
At U.S. Geological Survey gaging station No, 262 1,200 2,800 5,400 7,000 At U,S. Highway 1.01 3,03.0 5,55.0 5,75.0 5,95.0
Downstream of Interstate Highway 28.0 1,110 4,46.0 .5,460 7,310 Downstream of Junipero Serra 1,55.0 3,200 5,58.0 7,650
Downstream of Stevens Creek Dam 1,14.0 4,44.0 5,280 6,94.0 Downstream of Railroad 2,750 5,350g 5,350g 5,350g
Upstream of Junipero Serra 1,5.0.0 3,150 5,500 7,500
Upstream of Permanente Diversion 1,750 3,6.0.0 6,000 8,2.00 Upstream of Railroad 2,750 6,11.0 7,36.0 9,61.0

SUNNYVALE EAST CHANNEL
Downstream of Caribbean Drive b b 1,1 .0.0 b

SUNNYVALE WEST CHANNEL
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OFFICE OF EMERGENCY SERVICES

COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
. . Discharge (cubic feetJsecond)
Flooding Source and Location 10 50 Y 100 Y 1500 Y -year - ear - ear - ear Downstream of Highway 237 b b 360 b

TENNANT CREEK
Approximately 1,250 feet upstream of Hill Avenue b b 420 b Downstream of Maple Avenue b b 650 b
Upstream of confluence with East Little Llagas Creek b b 2,015 b

THOMPSON CREEK
2,000 feet downstream of Aborn Road 1,440 2,550 3,000 3,700 At Aborn Road 1,440 2,350 2,700 3,250
At Quimby Road 1,480 1,9008 1,9008 1,9008
Downstream of Verba Buena Creek 1,060 1,750 1,950 2,400

UPPER PENITENCIA CREEK
At Capitol Avenue 11,3508 1,3508 1,3508 1,3508
At confluence with Coyote Creek 1,110 1,110 1,110 1,110 At Gridley Street 1,460 3,050 3,600 4,950
Upstream of North Jackson Avenue 1,3508 .1,3508 1,3508 1,3508 At King Road 9608 9608 9608 960b
At Mabury Avenue 1,0508 1,0508 1,0508 1,0508
At Upper Penitencia Road 1,460 2,8108 2,9508 2,9508
At U.S. Geological survey gage at Dorel Road 1,400 2,940 3,600 5,170

UVASCREEK
At confluence with Bodfish Creek b b 10,910 b
At confluence with Little Arthur Creek b b 8,500 b
At downstream face of Watsonville Road Bridge b b 10,360 b At Thomas Road b b 14,000 b
At Railroad b b 5,2003 b
At U.S. Highway 101 b b 8,0003 b
At Uvas Road b b 7,800 b
Downstream of Hecker Pass Road b b 13,550 b
Downstream of Santa Teresa Boulevard b b 14,000 b
UVAS CREEK - EAST OVERBANK ABOVE HIGHWAY 101
Approximately 1,200 feet above U.S. Highway 101 q b 2,200 b At U.S. Highway 101 q b 1,100 b

UVAS CREEK - EAST OVERBANK ABOVE RAILROAD
At downstream limit of flooding q b 3,200 b
At upstream limit of flooding q b 2,100 b

WATSON ROAD OVERFLOW AREA
At convergence with Llagas Creek b b 447 b
At divergence from West Little Llagas Creek b b 97 b

WEST BRANCH LLAGAS CREEK
Downstream of divergence from West Branch Llagas Creek - East Split b b 160 b Upstream of divergence from West Branch Llagas Creek - East Split b b 1,400 b

WEST BRANCH LLAGAS CREEK - LOWER SPLIT
At Day Road Interceptor (NRCS PL566) q b 1,200 b

WEST BRANCH LLAGAS CREEK - MIDDLE SPLIT
Downstream of Highland Avenue q q 80 q

WEST BRANCH LLAGAS CREEK - UPPER SPLIT
Upstream of Highland Avenue q q 200 q
178 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
. Discharge (cubic feet'second)
Flooding Source and Location 10 150 Y 100 Y 500 Y

WEST LITTLE LLAGAS CREEK
1,000 feet upstream of Wright Avenue
At Fourth Street
At U.S. Highway 101
Downstream of Edmundson Avenue
Downstream of Monterey Highway
Downstream of Railroad
Upstream of Llagas Avenue
Upstream of Monterey Highway
Upstream of Seymour Avenue

WILDCAT CREEK
Above Portos Drive
At Saratoga and Los Gatos Roads
Below Douglas Lane

MAYFIELD SLOUGH
At Embarcadero Road

SAN FRANCISCO BAY
At confluence of Guadalupe Slough and Coyote Creek
At crossing of Railroad and Alviso Slough
At Milpitas
At Mountain View
At Palo Alto
At Sunnyvale
a. Decrease in flow rate based on capacity restrictions b. Data not available/computed
c. Discharge decrease due to Barron Creek Diversion
d. Flow rate accounts for upstream channel spills
e. Slow rate reflects upstream capacity restriction
f. Flow influenced by spill from adjoining watercourse
g. Flow reduction due to bridge or channel capacity restriction h. Increase in flow rate due to spills from neighboring subbasins Flow rate reduction due to attenuation in the floodplain j. Reduction in flood rate due to storage behind railroad

WARNING TIME
- ear - ear - ear I - ear
a )8 1882 a
a a 9002 8
a a .1,080b a
a a 1,269 8
8 a 8132 a
a a 4602 a
a a 1,702b 8
a a 1,936 8
a a ,1,770b 8
480 810 960 1,230
310 500 570 740
430 710 840 1,070

10.00 a 10.5 10.8
b b 10.8 b
b b 11.3 b
b b 11.4 b

10.2 b 10.7 11.0

9.9 b 10.5 10.8

3.7 ,b ' 10.7 b
k. Flow rate reduction due to attenuation in reservoirs I. High flows affected by Permanente Diversion
m. Decrease in flow rate due to storage along channel
n. High flows diverted to Stevens Creek
o. Logarithm extrapolation
p. Flow rate reduction due to storage in Lake Cunningham q. Flooding due to spill- drainage area not applicable
Potential warning time available to a community for response to a flooding threat depends on the time span between the first measurable rainfall and the first occurrence of flooding. The time duration necessary to recognize a flooding threat reduces potential warning time for a community that must take actions to protect lives and property. Another element that characterizes a community's flood threat is length of time floodwaters remain above flood stage.

Because of the sequential pattern of weather conditions needed to cause serious flooding, occurrence of a flood without warning is unusual. Warning times for floods can be between 24 and 48 hours. Flash flooding can be less predictable, but populations in potential hazard areas can be warned in advance of flash flooding danger. NWS issues watches and warnings when forecasts indic ate rivers may approach bank-full levels. Flood extent or severity categories used by NWS include minor flooding, moderate flooding, and major flooding, based on property damage and public threat (NWS, 2011):
10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1179

OFFICE OF EMERGENCY SERVICES

COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
• Minor Flooding - Minimal or no property damage, but possibly some public threat or inconvenience.
• Moderate Flooding-Some inundation of structures and roads near streams. Some necessary evacuations of people and/ or transfer of property to higher elevations. • Major Flooding-Extensive inundation of structures and roads. Significant evacuations of people and/ or transfer of property to higher elevations.

When a watch is issued, the public should prepare for the possibility of a flood. When a warning is issued, the public is advised to stay tuned to a local radio station for further information and be prepared to take quick action if needed. A warning means a flood is imminent, generally within 12 hours, or is occurring.

Local media broadcast NWS warnings. Thresholds for flood warnings have been established on some of the major rivers in Santa Clara County, based on available stream gage information. Current stream flows are gathered from the following USGS stream gauges in the county (USGS, 2017b). • USGS 11153000 Pacheco Creek, Dunneville, CA.
• USGS 11153650 Llagas Creek, Gilroy, CA.
• USGS 11164500 San Francisquito Creek, Stanford University. • USGS 11166000 Matadero Creek, Palo Alto, CA.
• USGS 11169025 Guadalupe River along Highway 101, San Jose, CA. • USGS 11169500 Saratoga Creek, Saratoga, CA.
• USGS 11169800 Coyote Creek, Gilroy, CA.
• USGS 11172715 Coyote Creek along Highway 237 at Milpitas, CA. • USGS 11173200 Arroyo Hondo, San Jose CA.

SECONDARY HAZARDS
The most problematic secondary hazard for flooding is bank erosion, which in some cases can be more harmful than actual flooding. This is especially true in the upper courses of rivers with steep gradients, where floodwaters may pass quickly and without much damage, but scour the banks, edging properties closer to the floodplain or causing them to fall in. Flooding is also responsible for hazards such as landslides when high flows over-saturate soils on steep slopes, causing them to fail. Hazardous materials spills are also a secondary hazard of flooding if storage tanks rupture and spill into streams, rivers or storm sewers.

EXPOSURE
The Level 2 Hazus protocol was used to assess flood risk in the OA. The model used census data at the block level and FEMA floodplain data, which has a level of accuracy acceptable for planning purposes.

Where possible, the Hazus default data was enhanced using local GIS data from local, state and federal sources.

Population
Population counts of those living in the floodplain within the OA were generated by estimating percent of residential buildings in each jurisdiction within the I-percent-annual-chance flood hazard areas and multiplying this by total population within the OA. This approach yielded an estimated population in the OA of 112,894 living within the 100-year floodplain (5.9 percent of the total OA population). Table 9-6 lists population estimates by jurisdiction living in the 10-percent, I-percent and 0.2-percent annual chance flood hazard areas.
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TABLE 9-6. POPULATION WITHIN THE 10-PERCENT, I-PERCENT AND O.2-PERCENT ANNUAL CHANCE FLOOD

HAZARD AREAS
10-Percent Annual chance j 1-percent Annual Chance O.2-Percent Annual Chance Flood Hazard Area Flood Hazard Area Flood Hazard Area JUrisdiction - -- -- -- - - - -- -- - -- -- - --- . --- -- Population % of Total Population % of Total Population % of Total Ex osedB Popu lation Ex osed a Popu lation Ex osed 8 Population Campbell 10
Cupertino 292
GiI~~y 4
los Altos 69
los Altos Hills 68
los Gatos 29
Milpitas '4,758
Monte Sereno 6
MO.rgan Hill 1,794
Mountain View 49
Palo Alto 9,499
San Jose 7,674
Santa Clara (city) 0
Saratoga 57
Sunllyvale 4,151
Unincorporated County 1,257
TlOtal 29: '

0.0%

0.5%

0.0%

0.2%

0.8%

0.1%

6.3%

0.2%

4.1%

0.1%

13.9%

0.7%

0.0%

0.2%

2.8%

1.4%
34 0.1%
310 0.5%
1447 0.8%
228 0.7%
106 1.2%
35 0.1%
117,998 23.8%
6 0.2%
2,021 4.6%
2,122 2.7%
17,186 25.2%
56,606 5.4%
6,897 5.6%
66 0.2%
6,312 4.3%
2,519 2.9%
Nan 5.9%
a. Represents percent of residential buildings exposed multiplied by estimated 2016 population.

PROPERTY
Structures in the Floodplain
50 10.1%
33,871 58.2%

40.630 73.6%
29,417 93.8%
7,960 91.9%
28,230 90.0%
45,594 60.4%
31 0.9%
40,149 92.0%
5,602 7.2%
68,135 ;99.9%
98,858 9.5%
100,893 81.5%
29,931
i

99.0%
111,924 75.4%
2,811 ,3.2%
Table 9-7, Table 9-8, and Table 9-9 summarize the total area of the 10-, 1-, and 0.2-percent-annual-chance flood hazard areas and the number of structures in each. The Hazus model determined that there are 8,033 structures within the 10-percent-annual-chance flood hazard area, 28,236 structures within the 1- percent-annual-chance flood hazard area, and 167,415 structures within the 0.2-percent-annual-chance flood hazard area. In the I-percent-annual-chance flood hazard area, about 92 percent are residential, and 8 percent are commercial, industrial or agricultural.

Exposed Value
Table 9-10, Table 9-11 and Table 9-12 and summarize the estimated value of exposed buildings in theOA.

This methodology estimated $16.8 billion worth of building-and-contents exposure to the 10-percent­ annual-chance flood, representing 3.5 percent of the total replacement value of the OA, $40.1 billion worth of building-and-contents exposure to the 1-percent-annual-chance flood, representing 8.4 percent of the total replacement value of the OA, and $200.4 billion worth of building-and-contents exposure to the 0.2-percent-annual-chance flood, representing 42 percent of the total. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1181

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TABLE 9-7. AREA AND STRUCTURES IN THE lO-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA ! Area In Floodplain ' Number 01 Structures In Ihe Flood Hazard Area JUrisdiction , . acres Residential Commercial I Industrial ,A nculture Rell Ion I Government Education Total C~mpbell '1 0 0 0 0 0 0 0 0
Cupertino 148 80 2 () 0 0 0 0 82
Gilroy 887 1 23 67 2 :0 0 0 93'
Los Altos 34 23 0 0 0 0 0 0 23
Los Altos Hills 80 23 0 0 0 '0 0 0 23
Los Gatos 152 9 0 0 0 0 0 0 9
Milpitas 317 1,096 28 0 0 1 0 0 1.125
Monte Sereno 3 2· 0 0 0 0 0 0 2
Morgan Hill 498 466 102 5 3 3 1 0 680
Mountain View 677 11 25 27 0 0 0 0 83
Palo Alto 2,188 ,2,637 113 67 0 4 0 8 21829
San Jose 12.160 1,668 111 29 0 9 0 3 1.820
Santa Clara (city) 103 :0 2 0 0 0 '0 0 2
Saratoga 68 20 0 0 0 0 0 21
Sunnyvale ~, 131 851 53 114 0 0 1.020
6,170 271 17 3 41 5 4 0 341
26618 7158 471 312 47 23 5 11 8,033
TABLE 9-8. AREA AND STRUCTURES IN THE l-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA JUrisdiction IArea In Floodplain I ~tructures I~ ~I~ od Hazard Area _ -'---1- _ _ _____ _ acres ReSidential Commercial Industnal A nculture Religion Government Education Total Campbell 93 9 5 0 0 0 0 0 1_
Cupertino 1,79 85 2 0 0 0 '0 0 81
Gilroy ; 1,794 100 61 78 2 0 0 0 241
Los Altos 91 76 0 0 0 ,0 0 77
Los Altos Hills ' 104 36 '0 0 0 0 10 0 38
Los Gatos 177 11 0 0 0 0 :0 0 11
Milpitas ' 1,531 4,146 90 135 0 2 '0 0 4;373
Monte Sereno 3 2 0 0 0 '0 0 '0 2
Morgan Hill 587 525 106 5 3 3 ,1 0 643
Mountain View 1,154 480 87 39 0 1 0 0 607
Palo Alto 3,112 4,771 137 69 0 8 0 19
San Jose 19,330 12,304 , 5~1 354 1 ,33 2 17
Santa 91ara (city) 953 1,502 '70 77 0 3 '0 ,0
Saratoga 84 23 0 0 0 :0 0
Sunnyvale 3,405 1,294 115 2 .0 1
Unincorporated Count 24,131 5 147 5 4 1
':otal 567'1.7 877 t04 57 7 28
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TABLE 9-9. AREA AND STRUCTURES IN THE O.2-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA (;upertino 10 0 19 ,4 :3 9,871
Gilroy 9,096 518 147 7 24 17 Is 91807
Los Altos 13,845 9,803 503 1 0 19 1 :5 ....

Los Altos Hills 15,271 2,704 11 0 18 4 0 i1 ~.7~8
Los Gatos 5,485 8,794 542 10 2 19 3 :30 .,.

Milpitas 5,225 10,.503 1433 287 0 13 4 j1 11,241
Monte Sereno 19 11 0 0 ,0 0 0 0 11
Morgan Hill 7,053 10,427 376 182 49 13 7 14
-Mountain View 2,092 1,267 126 43 0 3 0 ;0 1.439
Palo Alto 15.023 18,915 1026 158 15 52 6 122 .1 20,18t
San Jose 24,708 21,488 1141 618 3 38 10 :20 23,m
Santa Clara (city) 7,836 21,972 670 299 1 :33 2 ;26 23,003 Saratoga 7,540 10,492 196 0 8 17 3 10,717
Sunnyvale 9,637 22,945 530 152 2 126 4 [7 .-
Unincorporated County 26,221 606 38 5 156 5 4 ;2 8'6
2M 53
TABLE 9-10. VALUE OF STRUCTURES IN THE IO-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA Estimated Value Within the Floodplain % of Total Replacement JUrisdiction I Structure Contents Total Value
Campbell $0 $0 $0 0.0%
Cupertino $27,647,546 1$14,420,410 $42.067,956 0.3%
Gilroy $566,223,042 $716,782,132 $1,283,005,174 9.6%
Los Altos $9,351,180 $4,675,590 $14,026,770 0.2%
Los Altos Hills $16,383,887 $8,191,944 $24,575,831 0.8% Los Gatos . $3,704,359 $1,852,180 $5,556,539 0.1%
Milpitas $281,341,173 $173,296,707 $454,637,880 2.4%
Monte Sereno . $846,663 $423,331 $1,269,994 0.1%
Morgan Hill $328,112,270 $259,388,932 $587,501,203 5.3% Mountain View $516,073,912 $592,978,692 $1,109,052,604 4.4% Palo Alto $1,737,322,004 $1,460,635,068 $3,197,957,072 12.4% San Jose $2,162,328,492 $1,907,957,229 $4,070,285,722 1.9% Santa Clara (city) $33,273,884 1$33,273,884 $66,547,769 0.2% Saratoga $10,479,575 $5,871,764 $16,351,339 0.2%
Sunnyvale 1$2,603,248,582 $2,809,224,975 $5,412,473,557 12.6% Unincorporated County $317,538,668 1$260,462,301 $578,000,969 2.3% ~
• M1I $1 305%
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TABLE 9-11. VALUE OF STRUCTURES IN THE I-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA JUrisdiction I Estlm~t~ y alue wt!l1Jn the £loodp@ID ._ .. _ I % of Total Replacement I Structure Contents Total Value
Campbell $60,706,038 I $53,432,344 $114,138,382 1.0%
Cupe~ino $29,853,614 $15,~23,445 $45,377,059 0.3%
r
Gilroy $857,099,327 $978,830,296 $1,835,929,624 13.7%
Los Altos $47,522,858 $32,368,309 $79,891,167 0.9%
Los Altos Hills $23,030,568 $11 ,515,284 $34,545,851 1.1% Los Gatos $4,750,797 $2,375,399 $7,126,196 0.1%
Milpitas $1 ,914,405,204 $1,412,176,099 $3,326,581 ,303 17.4% Monte Sereno '$846,663 $423,331 $1 ,269,994 0.1%
Morg~n Hill $351,696,852 $272,045,135 $623,741,987 5.6% Mountain View $863,391,510 $891,948,249 $1 ,755,339,759 7.0% Palo Alto $2,634,825,080 $1 ,974,405,542 $4,609,230,622 17.9% San Jose $9,823,110,379 $8,298,299,926 $18,121,410,305 8.5% Santa Clara (city) $1,278,101,561 $1 ,148,481,943 $2,426,583,504 5.6% Saratoga $11,266,355 $6,265,'54 $17,531,509 0.2%
Sunnyvale $2,831 ,823,.587 $2,960,259,83.2 $5,792,083,419 13.5% Unincorporated County $713 062,623 1$608,794,293 $1 ,321 ,856,917 5.2% Total $21 445 493,017 $18667,144 581 $40,11.2,637,5'98 8.40/6 TABLE 9-12. VALUE OF STRUCTURES IN THE O.2-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA JUrisdiction , E~t!~1a.!e.d ~9IlJe_~lthH]. th.e FlooQpla!1"!. ._ _ _ __ _ I % of Total Replacement Structure Contents Total Value
Campbell $61,554,595 ! $ 5~,856 , 622 $115,411,217 1.0% Cupertino $6,,121,581,843 i $4,318,062,400 $10,439,644,243 75.2% Gilroy $5,817,785,372 $4,568L044,111 $10,385,829,483 77.5% Los Altos '$5,131,184,367 $3,2.22,243,127 $8,353,427,494 94.7% Los Altos Hills $1 ,872,115,137 $1 ,055,557,499 $2,927,672,637 90.3% Los Gatos ' $5,821,620,292 $4,274,397,260 $10,096,017,551 92.7% Milpitas $8,419,488,654 $7,360,099,766 $15,779,588,420 82.4% Monte Sereno $4,075,984 $2,037,992 $6,113,976 0.7%
Morgan Hill $6,037,072,687 $4,442,854,817 $10,479,927,505 93.9% Mountain View ; $1,729,570,951 : $1,584,953,565 $3,314,524,516 13.2% Palo Alto 1$14,329,115,228 : $11,343,355,359 $25,672,470,587 99.6% San Jose : $23,401 ,556,637 1$19,811,495,639 $43,213,052,276 20.3% Santa Clara (city) $14,681,795,650 $12,183,150,968 $26,864,946,619 61 .9% Saratoga $5,016,383,748 ~2,897,535, 178 $7,913,918,926 97.2% §..u_nnyvale $13,736,062,646 $9,589,591,988 $23,325,654,634 154.4% Unlncor orated Count '$790,512,159 $676,480,660 $1 ,466,992,819 5,8% Tail .11 971475949 $&7.383 716 953 ...

Land Use in the Floodplain
Some land uses are more vulnerable to flooding, such as single-family homes, while others are less vulnerable, such as agricultural land or parks. Table 9-13 and Table 9-14 show the existing land use for 184 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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unincorporated Santa Clara County parcels in the 1- and O.2-percent-annual-chance flood hazard areas, including vacant parcels and those in publici open space uses, broken down for the unincorporated portion of the OA. Only 0.54 percent of the parcels in the 1-percent-annual-chance flood hazar d area are zoned for agricultural uses . These are favorable, lower-risk uses for the floodplain. The amount of the floodplain that contains vacant, developable land is not known.

TABLE 9-13. UNINCORPORATED SANTA CLARA COUNTY LAND USE IN THE I-PERCENT ANNUAL CHANCE

FLOOD HAZARD AREA
T e of Land Use Area acres Percenta e of Total
~gricultural 13,680.3 54.69
General/Institutional 1,090.3 4.36 . . .

Open Sj:lace 8,444.8 33.76
Low Density Residential 1,799.1 7.19
High r;>en.sity Residential 0.0 0.00
Commercial 0.0 0.00
Industrial 0.0 10.00
Total 25.014.5 100,00
TABLE 9-14. UNINCORPOR ATED SANTA CLARA COUNTY LAND USE IN THE 0.2-PERCENT ANNUAL CHANCE

FLOOD HAZARD AREA
T e of Land Use Area acres Percenta e of Total
Agricultural 14,018.5 52.73
General/Institutional 1,122.4 4.22
Open Space 9,608.5 36.14
Low Density Residential 1,836.9 6.91
~igh Density R~sidelltial 10.5 0.00
Commercial 10.0 0.00
Industrial 0.0 0.00
TOhI 26586.9 Wo.te

CRITICAL FACILITIES AND INFRASTRUCTURE
Table 9-15, Table 9-16, and Table 9-17 summarize the critical facilities and infrastructure in the 10-, 1-, and 0.2-percent-annual-chance flood hazard areas. Details are provided in the following sections.

Toxic Release Inventory Reporting Facilities
Toxic Release Inventory (TRI) facilities are known to manufacture, process, store, or otherwise use certain chemicals above minim.um. tluesholds. If damag ed by a flood, th ese facilities could release chemicals that cause cancer or other human health effects, Significant adverse acute human health effects, or Significant adverse environmental effects (U.s. Environmental Protection Agency [EPA], 2015). During a flood event, containers holding these materials can rupture and leak into the surrounding area, disastrously affecting the environment and residents . Sixty-seven facilities within the 1-percent-annual-chance flood zone are TRI reporting facilities.
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TABLE 9-15. CRITICAL F ACILITIFS IN THE 10-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA Cu~ertino 5
Gilroy 1 5 0 0 4
Los Altos 0 6 0 0 ,0 0
Los Altos Hills 0 14 0 0 0 0
Los Gatos 0 8 0 0 0 0
Milpitas 3 0 0 ,5 0
Monte Sereno 0 0 0 0 0 0
Morgan Hill 0 6 0 0 7 0 13
Mountain View 0 7 0 10 0 2 9
Palo Alto 0 20 0 10 15 5 40
San Jose 2 70 0 10 6 1 '19
Santa Clara (city) 0 17 0 0 0 0 111
Saratoga 0 9 0 0 0 0 9
Sunnyvale 3 0 0 7 12
Unincorporated County 1 42 0 0 1 0 44
8 2'5 0 38 276
TABLE 9-16. CRITICAL FACILITIES IN THE 1-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA Cupertino 15 0 0 0 18
Gilroy 2 15 0 0 :0 4 21
Los Altos 0 15 0 0 '2 0 11
Los Altos Hills 0 ! 14 0 0 :0 0
Los Gatos 0 10 0 0 ,0 0
Milpitas 2 17 0 0 ~ 11
I 11
Monte Sereno 0 0 0 0 ;0 0
Morgan \:IiII_ 1 6 0 0 :7 0
Mountain View 2 34 0 0 0 3 i
Palo Alto 1 47 0 0 ' 22 5
San Jose 9 265 0 0 :44 25
Santa Clara (city) 1 50 0 0 ;4 13
Saratoga 0 13 0 0 :0 0
Sunnyvale 20 0 0 ;5 8
Unincorporated County 1 102 0 '3 0
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TABLE 9-17. CRITICAL FACILITIES IN THE 0.2-PERCENT ANNUAL CHANCE FLOOD HAZARD AREA Number of Facilities In the Flood plain _ _ _
Junsdlctlon Emergency Infra- Militar Recover SOCIO- . Hazardous Response I Public structure F 1/ Fit Y economi c M t I Total Health & Safet lifeline aCI lies aC11 les FaCilities a ena s 9ampbell 0 16 0 0 0 7
Cupertino. 6 30 0 0 34 3 7t
Gilroy 15 36 0 1 40 15 97
Los Altos 6 28 0 '0 36 0 70
Los Altos Hills 1 48 0 0 6 0 65
Los Gatos 14 39 0 '0 22 76
Milpitas 9 65 0 '0 33 '42 149
Monte Sereno 0 :0 10 0 0 10 0
Morgan Hill 9 12 0 0 37 7 65
Mountain View 3 41 '0 10 16 5 Sf
Palo Alto 19 70 10 ;0 195 22 206
San Jose 16 1312 0 !o 66 52 446
Santa Clara (city) 13 :63 0 10 85 43 204
S.aratoga 7 33 0 0 30 0 70
Sunnyvale 11 )39 0 i.o 73 16 139
1 106 0 0 3 0 110
reI 110 928 0 1 56" 196 1822
Utilities and Infrastructure
It is important to determine who may be at risk if infrastructure is damaged by flooding. Roads or railroads that are blocked or damaged can isolate residents and can prevent access throughout the OA, including for emergency service providers needing to get to vulnerable populations or to make repairs.

Bridges washed out or blocked by floods or debris also can cause isolation. Water and sewer systems can be flooded or backed up, causing health problems. Underground utilities can be damaged. Dikes can fail or be overtopped, inundating the land that they protect. The following sections describe specific types of critical infrastructure .

ROADS
The following major roads in the OA pass through the 1-percent-annual-chance flood zone and thus are exposed to flooding:
• US 101 • State Route 9 • State Route 87
• Interstate 280 • State Route 17 • State Route 152
• Interstate 680 • State Route 82 • State Route 237
• Interstate 880 • State Route 85
Some of these roads are built above the flood level, and others function as levees to prevent flooding.

Still, in severe flood events these roads can be blocked or damaged, preventing access to some areas.

INFRASTRUCTURE LIFELINES
Flooding events can significantly impact critical infrastructure lifelines such as highways, bridges, airports, water and wastewater facilities and communication facilities. An analysis showed that there are 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1187

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629 infrastructure lifelines (241 are bridges) that are in or cross over the 1-percent-annual-chance flood zone and 928 infrastructure lifelines in the O.2-percent-annual-chance flood zone.

WATER AND SEWER INFRASTRUCTURE
Water and sewer systems can be affected by flooding. Floodwaters can back up drainage systems, causing localized flooding. Culverts can be blocked by debris from flood events, also causing localized urban flooding. Floodwaters can get into drinking water supplies, causing contamination. Sewer systems can be backed up, causing wastewater to spill into homes, neighborhoods, rivers and streams.

LEVEES
SCVWD constructed flood protection levees in the north, central, and southern portions of the county, some of which provide 1-percent-annual-chance flood protection. The levees along Uvas Creek, King Creek, Lyons Creek, and Coyote Creek participate in Corps' Levee Program. Levees along the Guadalupe River do not participate. SCVWD does not believe the majority of levees could withstand intensities of a 1-percent annual chance flood. Additionally, coastal flooding from San Francisco Bay circumvents levees near the Bay. Moreover, current flood levels do not account for potential sea level rise, which would exacerbate vulnerability and further reduce the ability of the levees to prevent or reduce flooding.

The presence and effects of levee systems in the Santa Clara County OA are not reflected on the DFIRM, meaning that areas, structures, and populations vulnerable to failures of those levees cannot be determined. Levee failures could place large numbers of people and great amounts of property at risk.

Unlike dams, levees do not serve any purpose beyond providing flood protection and (less frequently) recreational space for residents. A levee failure could be devastating, depending on severity of flooding and amount of land development present. In addition to damaging buildings, infrastructure, trees, and other large objects, levee failure can result in significant water quality and debris disposal issues. Severe erosion is also a consideration.

ENVIRONMENT
Flooding is a natural event, and floodplains provide many natural and beneficial functions. Nonetheless, flooding can impact the environment in negative ways. Migrating fish can wash into roads or over dikes into flooded fields, with no possibility of escape. Pollution from roads, such as oil, and hazardous materials can wash into rivers and streams. During floods, these can settle onto normally dry soils, polluting them for agricultural uses. Human development such as bridge abutments and levees, and logjams from timber harvesting can increase stream bank erosion, causing rivers and streams to migrate into non-natural courses.

VULNERABILITY
Many of the areas exposed to flooding may not experience serious flooding or flood damage. This section describes vulnerabilities in terms of population, property, infrastructure, crops and environment.

POPULATION
Vulnerable Populations
A geographic analysis of demographics using the Hazus model identified populations vulnerable to the flood hazard as follows:
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• Economically Disadvantaged Populations-It is estimated that 9.99 percent of the people within the 100-year floodplain are economically disadvantaged, defined as having household incomes of $20,000 or less.
• Population over 65 Years Old - It is estimated that 11.3 percent of the population in the census blocks that intersect the 100-year floodplain are over 65 years old. • Population under 16 Years Old-It is estimated that 24.0 percent of the population within census blocks located in or near the 100-year floodplain are under 16 years of age.

Additionally, it is estimated that on a normal work day 100,000 Santa Clara County residents commute out of the county and 200,000 non-residents commute in. These commuters are considered vulnerable to the flood hazard. Commuters whose workplaces or major transportation routes are in or near the 1- percent-annual-chance flood zone may be especially vulnerable.

Estimated Impacts on Persons and Households
Impacts on persons and households in the OA were estimated for the 10-, 1-, and 0.2-percent-annual­ chance flood events through the Level 2 Hazus analysis. Table 9-18 summarizes the results.

TABLE 9-18. ESTIMATED FLOOD IMPACT ON PERSONS AND HOUSEHOLDS Number of D!~Rlace<:!J:1 0u ~_; Number of Pers9..~.~.~~.i~~ort- Term Shelter JUrisdiction 10% Annual 1 % Annual lo 2% Annual!1 00;' A 1110;' A I 02°;' A I Chance Chance Chance I ° nnua ° nnua. ° nnua Flood Flood 1 Flood : Chance Flood : Chance Flood Chance Flood Campbell 10 3 4 0 2 2
Cupertino 41 34 26,940 37 28 126,952
Gilroy 0 96 37,365 0 80 36,429
Los Altos 5 21 ' 27,996 11 27 ~548
Los Altos Hills 2 i3 7,3114 0 0 6,980
Los Gatos 3 :3 25,104 2 2 24,167 -
Milpitas 1,466 [7,895 38,643 .1,407 7,563 t38,147
Monte Sereno 0 ;0 1 0 0 0
Morgan Hill 547 i572 37,516 490 510 36,590
Mountain View 7 :315 1,554 2 251 1,390
Palo Alto 7,704 18,879 68,050 7,516 8,421 66,730
San Jose 2,081 1,925 44,795 1,913 1.796 42,637
Santa Clara (city) 0 2.127 93.108 0 1,966 191 ,881
Saratoga 3 3 29.602 1 28.997
Sunnyvale 2,982 2,693 2,845
Unincorporated County 130 315
Tetal !Jill,. V9~
Public Health and Safety
Floods and their aftermath present numerous threats to public health and safety:
• Unsafe food - Floodwaters contain disease-causing bacteria, dirt, oil, human and animal waste, and farm and industrial chemicals. Their contact with food items, including food crops in agricultural lands, can make that food unsafe to eat. Refrigerated and frozen foods are affected during power outages caused by flooding. Foods in cardboard, plastic bags, jars, bottles, and paper packaging may be unhygienic with mold contamination. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1189

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• Contaminated drinking and washing water and poor sanitation - Flooding impairs clean water sources with pollutants. The pollutants also saturate into the groundwater. Flooded wastewater treatment plants can be overloaded, resulting in backflows of raw sewage. Private wells can be contaminated by floodwaters. Private sewage disposal systems can become a cause of infection if they or overflow.
• Mosquitoes and animals - Floods provide new breeding grounds for mosquitoes in wet areas and stagnant pools. The public should dispose of dead animals that can carry viruses and diseases only in accordance with guidelines issued by local animal control authorities.

Leptospirosis-a bacterial disease associated predominantly with rats-often accompanies floods in developing countries, although the risk is low in industrialized regions unless cuts or wounds have direct contact with disease-contaminated floodwaters or animals. • Mold and mildew - Excessive exposure to mold and mildew can cause flood victims ­ especially those with allergies and asthma - to contract upper respiratory diseases, triggering cold-like symptoms. Molds grow in as short a period as 24 to 48 hours in wet and damp areas of build~gs and homes that have not been cleaned after flooding, such as water-infiltrated walls, floors, carpets, toilets and bathrooms. Very small mold spores can be easily inhaled by human bodies and, in large enough quantities, cause allergic reactions, asthma episodes, and other respiratory problems. Infants, children, elderly people and pregnant women are considered most vulnerable to mold-induced health problems. • Carbon monoxide poisoning-In the event of power outages following floods, some people use alternative fuels for heating or cooking in enclosed or partly enclosed spaces, such as small gasoline engines, stoves, generators, lanterns, gas ranges, charcoal or wood. Built-up carbon monoxide from these sources can poison people and animals. • Hazards when reentering and cleaning flooded homes and buildings - Flooded buildings can pose significant health hazards to people entering them. Electrical power systems can become hazardous. Gas leaks can trigger fire and explosion. Flood debris - such as broken bottles, wood, stones and walls - may cause injuries to those cleaning damaged buildings. Containers of hazardous chemicals may be buried under flood debris . Hazardous dust and mold can circulate through a building and be inhaled by those engaged in cleanup and restoration. • Mental stress and fatigue-People who live through a devastating flood can experience long­ term psychological impact. The expense and effort required to repair flood-damaged homes places severe financial and psychological burdens on the people affected. Post-flood recovery can cause, anxiety, anger, depression, lethargy, hyperactivity, and sleeplessness. There is also a long-term concern among the affected that their homes can be flooded again in the future.

Current loss estimation models such as Hazus are not equipped to meaSllfe public health impacts such as these. The best preparation for these effects includes awareness that they can occur, education of the public on prevention, and planning to deal with them during responses to flood events.

PROPERTY
Structures and Contents
Hazus calculates losses to structures from flooding by looking at depth of flooding and type of structure.

Using historical flood insurance claim data, Hazus estimates the percentage of damage to structures and their contents by applying established damage functions to an inventory. For this analysis, local data on facilities was used instead of the default inventory data provided with Hazus. The analysis is 190 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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summarized in Table 9-19, Table 9-20 and Table 9-21 for the 10-, 1-, and 0.2-percent-annual-chance flood events, respectively.

TABLE 9-19. Loss ESTIMATES FOR 10-PERCENT-ANNUAL-CHANCE FLOOD Structures I Estimated Loss Associated with Flood I % of Total JUrisdiction I ' 1m acted 8 I Structure Contents Total Replacement Value Campbell 0 $0 $0 :$0 10.0%
Cupertino 3 $_11,144 $7,429 'S18,573 0.0%
Gilroy 3 Sl,317,398 $3,768,744 1$5;086,142 0.0%
Los Altos 2 $105,619 S53,714 $159,333 0.0%
Los Altos Hills 2 $68,121 $42,876 '$110,998 0.0%
Los Gatos 0 $0 $0 SO 0.0%
Milpitas 986 $43,135,138 $37,117,050 ! $80,252,189 0.4% Monte Sereno 1 $47,268 $29,165 ' $76 ,~33 0.0%
M_organ Hill 189 $5,527,952 $11,327,545 '$16,855,497 0.2% Mountain View 25 $4 , 86~ , 005 $8,260,107 '$13,128,112 0.1% Palo Alto 2,025 $199,314,582 ~ 245 , 524 , 051 ' $444,838,633 1.7% San Jose 966 $136,449,482 $236,308,663 $372,758,145 0.2% Santa Clara (city) 1 $1 ,338,585 $2,185,626 $3,524,211 0.0% Saratoga 1 $39,746 $14,453 $54,199 0.0%
Sunnyvale 408 $136,886,599 $305,316,148 '$442,202.747 1.0% Uninco orated County 91 $4,367,410 $6,513,733 : $10.881.143 0.0% Total 703 $93 11050 $856489306 '$1
--
8A
a. Impacted structures are those with finished floor elevations below the flood event water surface elevation. These structures are the most likely to receive significant damage in a flood event.

Note: Values shown are accurate for comparison of results in this plan, See Section 0 for discussion of data limitations.

TABLE 9-20. Loss EsTIMATES FOR I-PERCENT-ANNUAL-CHANCE FLOOD I Structures I Estimated Loss ASSOCiated With Flood % of Total JUrisdiction ' ----Impacted a ' Structure Contents Total Replacement Value Campbell 3 $16,926,865 $29,428,799 $46,355,665 0.4%
Cupertino 24 $1,052,781 $588,706 $1,641,487 0,0%
Gilroy 30 $6,689,735 $15,161,388 $21,851,123 0,2%
Los Altos 41 $9,402,307 $10,673,460 $20,075,767 0,2%
Los Altos Hills 3 $121,654 $73,603 $195,257 0,0%
Los Gatos 0 $0 $0 $0 0,0%
Milpitas 1,803 i $51,494,330 , $46,269,246 $97,763,576 0.5% Monte Sereno 1 ' $97,424 $55,018 $152,442 0.0%
Morgan Hill 207 .$7,087,165 $13,899,757 $20,986,921 0.2% Mountain View 244 $9,745,617 ,$14,874,352 $24,619,969 0.1% Palo Alto 3,023 ' $224,950,926 $288,040,109 $512,991,035 2.0% San Jose 7,258 $321,601,980 ' $525,105,450 $846,707,430 0.4% Santa Clara (city) 844 $13,146,658 $17,557,461 $30,704,119 0.1% SO;1ratoga 3 $92,280 $57,599 $149,879 0.0%
Sunnyvale 794 $150,768,106 $320,868,331 $471,636,438 1.1% Unincorporated County 346 $75,915,605 $100,008,535 $175,924,140 0.7% t~ f 'Baa .~ 382 681 8~6 ,$2 ~ .I~
a. Impacted structures are those with finished floor elevations below the flood event water surface elevation. These structures are the most likely to receive significant damage in a flood event.

Note: Values shown are accurate for comEarison of results in this Elan, See Section 0 for discussion of data limitations. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1191

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TABLE 9-21. Loss ESTIMATES FOR 0.2-PERCENT-ANNUAL-CHANCE FLOOD I Structures Estimated Loss Associated with Flood % of Total JUrisdiction - - l - - - -1- - - - -11m acted a Structure Contents Total Replacement Value Campbell 18 1$17,093,500 ! $29,500,064 $46,593,564 0.4% Cupertino 5,398 $1,022,251,503 . $952,596,401 $1,974,847,904 14.2% Gilroy 15>i98 $772,578,473 ~965,570,283 $1,738,148,756 13.0% Los Altos 4,047 $467,470,569 $405,893,093 $873,363,662 9.9% Los Altos Hills 889 $365,547,411 $225,030,872 $590,578,283 18.2% Los Gatos 5,626 .$1,809,407,428 $1,694,708,840 $3,504,116,269 32.2% Milpitas 5,881 i $335.288,895 $426.087.597 $761,376,492 4.0% Monte Sereno 5 ·$174,826 $102,546 $277,371 0.0%
Morgan Hill 6,339 i$1 ,082, 158,998 i $955,615,585 $2,037,774,583 18.3% Mountain View 751 :$40,575,174 1$47,979,623 $88,554,797 0.4% Palo Alto 15,514 1$2,297,621 ,503 I $.2 , ~82 ! 440 , 183 $4,980,061,686 19.3% San Jose 12,992 i-$824, 133,41 0 $1,140,183,083 $1,964,316,492 0.9% Santa Clara (city) 11,358 : $708,522,448 $740,423,216 $1,448,945,665 3.3% Saratoga 3.235 i $846,879,388 $555.'7'60.836 $1,402,640,224 17.2% Sunnyvale 8,468 $707.246.874 $869,214.144 $1,576,461,018 3.7% Unincorporated County 607 1$101.251522 $127,422.897 $228.674,420 0.9% Tdal 86616 Sf" &1 Sf 1311 •• 4.8%
a. Impacted structures are those with finished floor elevations below the flood event water surface elevation. These structures are the most likely to receive significant damage in a flood event.

Note: Values shown are accurate for comparison of results in this plan. See Section 0 for discussion of data limitations.

Key results are as follows:
• There would be up to $1.39 billion of flood loss from a 10-percent-annual-chance flood event in the OA. This represents 3.5 percent of the total exposure to that level of flood and

0.3 percent of the total replacement value for the OA.
• There would be up to $2.27 billion of flood loss from a 1-percent-annual-chance flood event in the OA. This represents 8.4 percent of the total exposure to that level of flood and

0.5 percent of the total replacement value for the OA. . • There would be $23.22 billion of flood loss from a 0.2-percent-annual-chance flood event in the OA. This represents 42 percent of the total exposure to a that level of flood and 4.9 percent of the total replacement value.

Flood-Caused Debris
The Hazus analysis estimated the amount of flood-caused debris within the OA generated by flooding, as summarized in Table 9-22.

Estimate of Crop losses
According to the USDA's Risk Management Agency, the amount of claims paid for crop damage as a result 'of flood in Santa Clara County over a 14-year period was $8,200,676. According to the 2016 California Insurance Profile from the USDA's Risk Management Agency, 54 percent of the insurable crops in California are insured with USDA Crop Insurance. To provide an adjusted estimate of losses accounting for insurable crops that are not insured, the 54 percent crop insurance coverage was factored 192 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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in. According to this calculation, estimated annualized losses are almost $1 million (see Table 9-23).

Considering the value of crops from the 2012 Census of Agriculture as baseline crop exposure, the estimated annual loss from flood was determined to be low compared to the value of the insurable crops.

TABLE 9-22. ESTIMATED FLOOD-C AUSED DEBRIS
1 0% A~n_ual-Chance Flood_ 1J~ _Ar1nuC3I-CJ!ance ~ I' O,2%~_ ~nnual .. Chance Flood_ J d t Debris to Be Estimated Debris to Be Estimated Debris to Be I Estimated UriS IC Ion Removed Number of Removed Number of l Removed Number of tons)8 Truckloads b ton s)8 Truckloads b (tons)8 Truckloads b Campbell 10 0
Cupertino 201 18
Gilroy 246 10
Los Altos 118 5
Los Altos Hills 52 12
Los Gatos 130 5
Milpitas 4,977 199
Monte Sereno 11 0
Morgan Hill 1,072 43
Mountain View 129 15
Palo Alto 15,047 602
San Jose 23,022 921
Santa Clara (city) 216 9
Saratoga 420 17
Sunnyvale 1,223 49
Unincor orated County 1,113 45
letaI eMS 1l9U
2,958
1,258
1,317
998
93 1,934
9,638
14 1,480
'1,867
20,323
79,315
10,367
678
3,386
8,721
144344
1118
50 53
40 4
77 386
1 59
75 813
3,173
415
27 135
349
5774
3,051
186,456
46,923
82,064
81c669
553,516
17,375
100
143,514
3,190
199,656
,96,082
i63,338
217,199
42,176
13,384
1749.694
122
7,458
1,877

3.283
3,267
22,141
695
4 5,741
128
7,986
3,843
2,534
8,688
1,687
535
..
a. Debris generation estimates were based on updated general building stock dataset at a Census Block analysis level. b. Hazus assumes 25 tons/trucks.

Note: Values shown are accurate for comparison of results in this plan. See Section 0 for discussion of data limitations.

TABLE 9-23. ESTIMATED INSURABLE ANNU AL CROP Loss RESULTING FROM FLOOD 14-Year Flood Insurance Adjusted 14-year Flood Losses Estimated Annualized 2012 V I e of Cra sb Pald8 (considerin g 54% Insured ) Losses au p
$8,200,676 $13,524,077 $966,005 $233,397,000
a. Crop insurance paid from USDA's Risk Management Agency for 2003-2016. b. 2012 Census of Agriculture, Santa Clara County
Flood Insurance Statistics
Table 9-24 lists flood insurance statistics that help identify vulnerability in the OA. All 16 municipal planning partners participate in the NFIP, with 17,129 flood insurance policies providing $4.5 billion in insurance coverage. According to FEMA statistics, 784 flood insurance claims were paid between January 1,1978 and October 31, 2016, for a total of $14.773 million, an average of $18,843 per claim.

Properties constructed after a FIRM has been adopted are eligible for reduced flood insurance rates. Such structures are less vulnerable to flooding since they were constructed after regulations and codes were adopted to decrease vulnerability . Properties built before a FIRM is adopted are more vulnerable to flooding because they do not meet code or are located in hazardous areas. The first FIRMs in the OA were available in 1975.
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TABLE 9-24. FLOOD INSURANCE STATISTICS
Date of Entry # of FIOOd!1 I ' Total Claims . Value of Claims nsurance n JUrisdiction Initial FIRM I Insurance PoliCies F Annual 11/1978 to paid . 1111978 to Effective Date as of 1013112016 orce Premium 1013112016 10131/2016 Campbell 06/30/1976 81 1$22,646,000 1$44,916 0 1$0
Cupertino 04/18/1975 143 $43,735,900 $102,495 10 $812,171 Gilroy 06/04/1976 205 $75.006,900 $243,840 22 $302,117
los Altos 09/24/1976 83 $25,087,400 $62,551 5 $31,535 , los Altos Hills 11/26/1976 191 $58,726,800 $132,576 5 $37,478 los Gatos 02/27/1976 149 $44,538,700 $74,818 10 $51,957 Milpitas 03/28/1975 1,592 $403,981,100 $1 ,663,220 20 $75,336 Monte Sereno 05/18/2009 21 $6,972,000 $7,833 2 $41,974
Morgan Hill 06/18/1980 557 $159,125,300 $506,690 43 $482,726 Mountain View 09/19/1975 601 $174,867,300 $499,833 5 $10,920 Palo Alto 09/06/1989 3,609 $944,663,200 $4,125,112 369 $8,984,658 San Jose 04/09/1976 7,644 $1,913,467,400 $6,718,976 267 $3,537,348 Santa Clara (city) 02/11/1977 995 $291,146,100 $736,663 14 '$309,753 Saratoga 11/28/1975 175 $56,346,900 $87,375 7 $26,681
Sunnyvale ! 12/05/1975 1,083 $280,813,500 $998,078 5 $68,655 Unincor orated County 06/20/1978 634 $157454,000 $848,200 84 $1 ,506,977 Total 17129 $4,501124,500 $18 004,976 784 14773309
The following information from flood insurance statistics is relevant to reducing flood risk:
• The use of flood insurance in the OA is above the national average. Sixty percent of insurable buildings in the OA are covered by flood insurance. According to an NFIP study, about 49 percent of single-family homes in special flood hazard areas are covered by flood insurance nationwide.
• The average claim paid in the OA represents less than 1 percent of the 2016 average replacement value of structures in the floodplain.
• The percentage of policies and claims outside a mapped floodplain suggests that not all of the flood risk in the OA is reflected in current mapping. Based on information from the NFIP, 94 percent of policies in the OA are on structures within an identified SFHA, and 6 percent are for structures outside such areas. Of total claims paid, 11 percent were for properties outside an identified 100-year floodplain.

Repetitive loss and Severe Repetitive loss
A repetitive loss property is defined by FEMA as an NFIP-insured property that has experienced any of the following since 1978, regardless of any changes in ownership:
• Four or more paid losses in excess of $1,000.
• Two paid losses in excess of $1,000 within any rolling 10-year period. • Three or more paid losses that equal or exceed the current value of the insured property.

A severe repetitive loss property is further defined as follows:
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• Four or more paid losses in excess of $5,000 each, with the cumulative amount of such claim payments exceeding $20;000.
• At least two separate claim payments made, with the cumulative amount of the building portion of such claims exceeding the market value of the building. • At least two of the above referenced claims occurred within any rolling 10-year period and must be more than 10 days apart.

Repetitive loss properties make up only 1 to 2 percent of flood insurance policies in force nationally, yet they account for 40 percent of the nation's flood insurance claim payments. The government has instituted programs encouraging communities to identify and mitigate the causes of repetitive losses. A recent report on repetitive losses by the National Wildlife Federation found that 20 percent of these properties are outside any mapped 100-year floodplain. The key identifiers for repetitive loss properties are the existence of flood insurance policies and claims paid by the policies.

FEMA-sponsored programs, such as the CRS, require participating communities to identify repetitive loss areas. A repetitive loss area is the portion of a floodplain holding structures that FEMA has identified as meeting the definition of repetitive loss. Identifying repetitive loss areas helps to identify structures that are at risk but are not on FEMA's list of repetitive loss structures because no flood insurance policy was in force at the time of loss.

Monterey
Bay
4 8
Figure 9-3.

Repetitive Loss Areas
in the Operational Area
Repetitive Loss Areas
o Santa Clara Counly Boundary
D Counly Boundaries
Water Bodies & Channels
FlOOd n~urCS .:trt.:.. ill deple'.d on FEMA
Dlgllallnsurance Rate Maps (DFIRMI
~TETRATECH
16 Map Data SOu"'": Sanla Clar' County,
Miles Camans, FEMA, USDA
Figure 9-3 shows the repetitive loss areas in the Santa Clara County OA. FEMA's list of repetitive loss 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1195

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properties identifies four such properties in the OA as of November 16, 2016. The breakdown of the properties by jurisdiction is presented in Table 9-25.

TABLE 9-25. REPETITIVE Loss PROPERTIES
JUrisdiction Number of Repetitive Loss Pro erties Number of Severe Re etltlve Loss Properties Morgan Hili
Palo Alto
San Jose
Unincor orated County
Total t
Based on FEMA Region IX Report of Repetitive Losses, 11/16/2016 1 1
3 A review of the repetitive loss list indicated that none of the properties are outside the OA's special flood hazard area. The average claim paid for these four properties was $19,741, which is approximately 2 percent of the median home value for Santa Clara County ($982,500 according to Zillow.com as of 1/31/2017). This damage level would correlate to shallow flooding of less than 1 foot, which would appear appropriate for flood damage associated with stormwater or urban drainage issues. Although this suggests localized causes of repetitive flooding for the four properties, the fact that all four properties are in an identified special flood hazard area indicates that the flood risk is more than localized. With the potential for flood events annually, all of the mapped floodplain is considered to be susceptible to repetitive flooding.

CRITICAL FACILITIES AND INFRASTRUCTURE
Hazus was used to estimate the flood loss potential to critical facilities exposed to the flood risk. Using depth/ damage function curves to estimate the percent of damage to the building and contents of critical facilities, Hazus correlates these estimates into an estimate of functional down-time (the estimated time it will take to restore a facility to 100 percent of its functionality). This helps to gauge how long the OA could have limited usage of facilities deemed critical to flood response and recovery. 196 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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16 \. __ ..:==== _____ Mlles
FIGURE 9-3. REPETITNE Loss AREAS IN THE OPERATIONAL AREA 10/15/17 Santa Clara County Operational Area Mitigation Plan Figure 9·3.

Repetitive Loss Areas
in the Operational Area
1% Annual Chance (100-Year)
Flood Zone

0.2% Annual Chance (500-
Year) Flood Zone
Repetitive Loss Areas
o Santa Clara County Boundary
o County Boundaries
Water Bodies & Channels
Fk>od hazard ..... s IS dlplcl.d on FEMA
Dlgnallnsura ... Rat. Maps (DFIRM)
~ TETIIA TECH
Map Data SOurces: Santa Clara County.
camans. FEMA. USDA

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The Hazus critical facility results are as follows (see Table 9-26 through Table 9-28):
• 100-year flood event-On average, critical facilities would receive 6.36 percent damage to the structure and 23.35 percent damage to the contents during a 100-year flood event. The estimated time to restore these facilities to 100 percent of their functionality is 501 days. • SOO-year flood event- A SOO-year flood event would damage the structures an average of

13.58 percent and the contents an average 28.93 percent. The estimated time to restore these facilities to 100 percent of their functionality after a SOD-year event is 571 days.

TABLE 9-26. ESTIMATED DAMAGE TO CRITICAL FACILITIES AND INFRASTRUCTURE FROM THE 10% ANNUAL

CHANCE FLOOD
Number Ofi
I F I t Average % of Total Value Damaged Days to 100% Type of Critical Facility aC11 les _ _ _ _ _ _ _ Affected Buddin I Contents F unctlOnalit
Emergency Response I Public Health & Safety 2 ' 12.36 43.03 555 Infrastructure Lifeline 83 0.63 33.58 N/A
Military Facilities 0 !N/A N/A N/A
Recovery Facilities 10 iN/A N/A N/A
28 i 14.26 138.92 494
15 12.04 25.37 N/A
128 9. &.12 D4
N/A = Not Applicable
TABLE 9-27. ESTIMATED DAMAGE TO CRITICAL FACILITIES AND INFRASTRUCTURE FROM THE 1 % ANNUAL

CHANCE FLOOD
I Number of l
I F I t Average % of Total Value Damaged Days to 100% Type of Critical Facility aCI lies .___ _ _ _ __ I Affected I BUlldin 1 Contents I Functlona lit
Emergency Response I Public Health & Safety 4 10.89 30.94 518 Infrastructure Lifeline 248 0.65 27.77 N/A
Military Facilities 0 N/A N/A N/A
Recovery Facilities 0 N/A N/A NIA
Socioeconomic Facilities 78 8.61 25.46 484
57 5.27 9.24 N/A
387 US 23,35 601
N/A = Not Applicable
TABLE 9-28. ESTIMATED DAMAGE TO CRITICAL FACILITIES AND INFRASTRUCTURE FROM THE 0.2% ANNUAL

CHANCE FLOOD
I
Number of i
f F F I t Average % of Total Value Damaged I Days to 100% Type 0 Critical aCllity aCllles _ _ __ _ __ _ : Affected BUlldln . Contents I Functlonal it
Emergency Response I Public Health & Safety 52 22.55 42.40 574 Infrastructure Lifeline 359 1.14 21.81 N/A
~lIitary Facilities 0 NIA N/A N/A
Recovery Facilities 1 15.52 24,33 N/A
Socioeconomic Facilities 342 19.37 39.98 568
Hazardous Materials 129 9.33 16.11 N/A
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I Number of l I
T f C I F I I F I t Average % of Total Value Damaged Days to 100% ype 0 ntlca aCI Ity aCI lies _ , : Affected BUilding Contents I Functlonahtx
TotIfIAv 13.58 28;93
N/A :: Not Applicable

ENVIRONMENT
The environment vulnerable to flood hazard is the same as the environment exposed to the hazard. Loss estimation platforms such as Hazus are not currently equipped to measure environmental impacts of flood hazards. The best gauge of vulnerability of the environment would be a review of damage from past flood events. Loss data that segregates damage to the environment was not available at the time of this plan. Capturing this data from future events could be beneficial in measuring the vulnerability of the environment for future updates .

Additionally, while the vulnerability assessment typically focuses on human vulnerability to flood events, the opposite is also worth noting. Floodplains have many natural and beneficial functions; however, due to negative impacts of floods, many structural and other measures have been devised to limit how far a floodplain can extend. Disruption of natural systems can have long-term consequences for entire regions; however, this potential impact has only recently been noted. Some well-known, water­ related functions of floodplains (noted by FEMA) include:
• Natural flood and erosion control • Filter nutrients and impurities from runoff • Provide flood storage and • Process organic wastes
conveyance • Moderate temperatures of water
• Reduce flood velocities • Groundwater recharge
• Reduce flood peaks • Promote infiltration and aquifer recharge • Reduce sedimentation • Reduce frequency and duration oflow surface • Surface water quality maintenance flows .
.Areas within the floodplain that typically provide these natural functions are wetlands, riparian areas, sensitive areas, and habitats for rare and endangered species

ECONOMIC IMPACT
Locations of flooding will undergo heaviest economic impact. Within these areas, renovations of commercial buildings may be necessary, disrupting associated services. Additionally, significant damage within agricultural areas may occur with destruction of crops and other agricultural products. The tourism industry may also be affected by major flood events, as popular vacation areas tend to overlap flood hazard zones. Finally, flooding can cause extensive damage to public utilities and disruptions to delivery of services. Loss of power and communications may occur; and drinking water and wastewater treatment facilities may be temporarily out of operation.

FUTURE TRENDS IN DEVELOPMENT
Santa Clara County has been one of the state's fastest growing counties over the past 10 years, averaging a 1 .21-percent increase in population per year from 2005 through 2015. The Silicon Valley job market continues to grow, and many young tech workers choose to live in an urban environment rather than commute from the suburbs.

The planning partners are equipped to handle future growth within flood hazard areas. All municipal planning partners have general plans that address frequently flooded areas in their safety elements. All 10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1199

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partners have committed to linking their general plans to this hazard mitigation plan. This will create an opportunity for wise land use decisions as future growth impacts flood hazard areas.

Additionally, all municipal planning partners are participants in the NFIP and have adopted flood damage prevention ordinances in response to its requirements. With over 60 percent of communities in the OA participating in the CRS program, there is incentive to adopt consistent, appropriate, higher regulatory standards in communities with the highest degree of flood risk. All municipal planning partners have committed to maintaining their good standing under the NFIP through actions identified in this plan. Communities participating or considering participation in the CRS program will be able to refine this commitment using CRS programs and templates as a guide.

Any areas of growth could be impacted by the flood hazard if located within the identified hazard areas.

The SCVWD intends to discourage development within vulnerable areas and! or to encourage higher regulatory standards on the local level.

SCENARIO
Historically, floods have regularly affected the Santa Clara County OA. The OA can expect noteworthy flooding about once a year, with a flash flood every 2 to 3 years. Duration and intensity of heavy winter rains and atmospheric river events that cause flooding may increase due to climate change. The floodplains mapped and identified for the Santa Clara County OA will continue to take the brunt of these floods. OA residents prepare themselves for flooding by seeking and receiving information, and by pursuing mitigation. Impacts of flood events should decrease as the OA continues to promote and implement hazard mitigation and preparedness.

The worst-case scenario would be a series of heavy rains or storm events during an atmospheric river event, particularly if the rains also occur at high tide. These rains could flood numerous areas within a short time. This could overwhelm the response and floodplain management capability within the OA, as the OA would be subject immediately to flash flooding and coastal flooding, with subsequent influences on the County's streams. Major roads could be blocked, preventing critical access for many residents and critical functions. High in-channel flows could cause water courses to scour, possibly washing out roads and creating more isolation problems. In the event of multi-basin flooding, Santa Clara County would not be able to make repairs quickly enough to restore critical facilities and assets.

ISSUES
The Core Planning Group has identified the following flood-related issues relevant to the OA:
• The extent of the flood-protection currently provided by flood control facilities (dams, dikes and levees) is not known due to the lack of an established national policy on flood protection standards.
• The levee system within the OA is not consistently adequate to mitigate effects of a I-percent annual chance flood.
• The risk associated with the flood hazard overlaps the risk associated with other hazards such as earthquake, landslide, mud slides and fishing losses. This provides an opportunity to seek mitigation alternatives with multiple objectives that can reduce risk for multiple hazards. • There is no consistency of land-use practices and floodplain management scope within the OA.
• How climate change will affect flood conditions in the OA is uncertain . 200 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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• More information is needed on flood risk to support the concept of risk-based analysis of capital projects.
• There needs to be a sustained effort to gather historical damage data, such as high water marks on structures and damage reports, to measure the cost-effectiveness of future mitigation projects.
• Ongoing flood hazard mitigation will require funding from multiple sources. • There needs to be a coordinated hazard mitigation effort between jurisdictions affected by flood hazards in the OA.
• Floodplain residents need to continue to be educated about flood preparedness and the resources available during and after floods.
• The concept of residual risk should be considered in the design of future capital flood control projects and should be communicated with residents living in the floodplain. • The promotion of flood insurance as a means of protecting private property owners from the economic impacts of frequent flood events should continue. • Existing floodplain-compatible uses such as agricultural and open space need to be maintained. There is constant pressure to convert these existing uses to more intense uses within the OA during times of moderate to high growth.
• The economy affects a jurisdiction's ability to manage its floodplains. Budget cuts and personnel losses can strain resources needed to support floodplain management. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 201

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LANDSLIDE/MASS MOVEMENT

GENERAL BACKGROUND
The U.S. Geological Survey defines landslides to include a wide range of ground movement, such as rock falls, deep failure of slopes, and shallow debris flows. Although gravity acting on an over-steepened slope is the primary reason for a landslide, there are other contributing DEFINITIONS factors.

Landslides and mudslides can be initiated by storms, earthquakes, fires, volcanic eruptions or human modification of the land . They can move rapidly down slopes or through channels, and can strike with little or no warning at avalanche speeds, posing a serious hazard to properties on or below hillsides.

When landslides occur - in response to such changes as increased water content, earthquake shaking, addition of load, or removal of downslope support-they deform and tilt the ground surface. The result can be destruction of foundations, offset of roads, breaking of underground pipes, or overriding of downslope property and structures.

The USGS defines land subsidence as the loss of surface elevation due to the removal of subsurface support. Tn California, the two principal causes for land subsidence are aquifer compaction due to excessive groundwater pumping and decomposition of wetland soils exposed to air after wetland conversion to farmland.

LANDSLIDE TYPES
Landslides are commonly categorized by the type of initial ground failure. Common types of slides are shown on Figure 10-1 through Figure 10-4 (Ecology, 2014). The most common is the shallow colluvial slide, occurring particularly in response to intense, short-duration storms. The largest and most destructive are deep-seated slides, although they are less common than other types.

Landslide-The movement of
masses of loosened rock and soil
down a hillside or slope. Slope
failures occur when the strength
of the soils forming the slope is
exceeded by the pressure, such
as weight or saturation, acting
upon them,
Mass Movement-A collective
term for landslides, debris flows,
and sinkholes.

Mudslide (or Debris Flow)-A
river of rock, earth, organic
matter and other materials
saturated with water. Mudslides
develop in the soil overlying
bedrock on sloping surfaces
when water rapidly accumulates
in the ground, such as during
heavy rainfall or rapid snowmelt.

Water pressure in the pore
spaces of the material increases
to the point that the internal
.strength of the soil is drastically
weakened. The soil's reduced
resistance can then easily be
overcome by gravity, changing
the earth into a flowing river of
mud Qr '{slurry,"
Mudslides (or debris flows) are rivers of rock, earth, organic matter and other soil materials saturated with water. They develop in the soil overlying bedrock on sloping surfaces when water rapidly accumulates in the ground, such as during heavy rainfall or rapid snowmelt. Water pressure in the pore spaces of the material increases to the point that the internal strength of the soil is drastically weakened.

The soil's reduced resistance can then easily be overcome by gravity, changing the earth into a flowing river of mud.

A debris avalanche (Figure 10-5) is a fast-moving debris flow that travels faster than about 10 miles per hour (mph). Speeds in excess of 20 mph are not uncommon, and speeds in excess of 100 mph, although rare, can occur, The slurry can travel miles from its source, growing as it descends, picking up trees, boulders, cars, and anything else in its path. Although these slides behave as fluids, they pack many times the hydraulic force of water due to the mass of material included in them, They can be among the most destructive events in nature.
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Large blocks of earth shift when
groundwater le"tels rise.

FIGURE 10-1. DEEP SEATED SLIDE
Mid·slope benches typically
indicate slide prone areas.

FIGURE 10-3. BENCH SLIDE
'r"
. "
\ :
, :
t.',
, ' .
o", .~ •
. , . . " .
. . .. , . -. .,.,',
A thin layer of soil and debris mo~es
rapidly down a steep slope.

FIGURE 10-2. SHALLOW COLLUVIAL SLIDE
A large slide cuts deep into the
slope, depositing tons of soil and
debris at the base.

FIGURE 10-4. LARGE SLIDE
. .
, '.
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Scar (area of initial failure)
Track (mayor may
not be eroded)
Zone of Deposition (Fan)
(May be 10005 of feet or
even miles from the
point of origin)
Soli or Colluvium
FIGURE 10-5. TYPICAL DEBRIS AVALANCHE SCAR AND TRACK
Landslides also include the following:
• Rock Falls - blocks of rock that fall away from a bedrock unit without a rotational component. • Rock Topples - blocks of rock that fall away from a bedrock unit with a rotational component. • Rotational Slumps - blocks of fine-grained sediment that rotate and move down slope. • Transitional Slides - sediments that move along a flat surface without a rotational component. • Earth Flows - fine-grained sediments that flow downhill and typically form a fan structure . • Creep-a slow-moving landslide often only noticed through crooked trees and disturbed structures.
• Block Slides - blocks of rock that slide along a slip plane as a unit down a slope.

LANDSLIDE MODELING
Two characteristics are essential to conducting an accurate risk assessment of the landslide hazard:
• The type of initial ground failure that occurs, as described above. • The post-failure movement of the loosened material ("run-out"), including travel distance and velocity.

All current landslide models-those in practical applications and those more recently developed-use simplified hypothetical descriptions of mass movement to simulate the complex behavior of actual flow.

The models attempt to reproduce the general features of the moving mass of material through measurable factors, such as base shear, that define a system and determine its behavior. Due to the lack of experimental data and the limited current knowledge about the behavior of the moving flows, landslide models use simplified parameters to account for complex aspects that may not be defined.

These simplified parameters are not related to specific physical processes that can be directly measured, and there is a great deal of uncertainty in their definition. Some, but not all, models provide estimates of the level of uncertainty associated with the modeling approach.

Run-out modeling is complicated because the movement of materials may change over the course of a landslide event, depending on the initial composition, the extent of saturation by water, the ground shape 2041 Page Santa Ctara County Operational Area Mitigation Plan 10/15/17

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of the path traveled and whether there is additional material incorporated during the event (Savage and Hutter 1991; Rickenmann & Weber, 2000; Iverson, 2004).

LANDSLIDE CAUSES
Mass movements are caused by a combination of geological and climate conditions, as well as encroaching urbanization. Vulnerable natural conditions are affected by residential, agricultural, commercial, and industrial development and the infrastructure that supports it. The following factors can contribute to landslide: change in slope of the terrain, increased load on the land, shocks and vibrations, change in water content, groundwater movement, frost action, weathering of rocks, and removing or changing the type of vegetation covering slopes.

Excavation and Grading
Slope excavation is common in development of home sites or roads on sloping terrain. Grading can result in slopes that are steeper than the pre-existing natural slopes. These steeper slopes can be at an increased risk for landslides. The added weight of fill on slopes can also result in an increased landslide hazard.

Small landslides can be fairly common along roads, in either the road cut or the road fill. Landslides below new construction sites are indicators of the potential impacts stemming from excavation.

Drainage and Groundwater Alterations
Water flowing through or above ground is often the trigger for landslides. Any activity that augments the amount of water flowing into landslide-prone slopes can increase landslide hazards. Broken or leaking water or sewer lines can be especially problematic, as can water retention facilities that direct water onto slopes. However, even lawn irrigation and minor alterations to small streams in landslide­ prone locations can result in damaging landslides. Ineffective stormwater management and excess runoff can also cause erosion and increase the risk of landslide hazards. Drainage can be affected naturally by the geology and topography of an area. Development that results in an increase in impervious surface impairs the ability of the land to absorb water and may redirect water to other areas. Channels, streams, flooding, and erosion on slopes all indicate potential slope problems.

Road and driveway drains, gutters, downspouts, and other constructed drainage facilities can concentrate and accelerate flow. Ground saturation and concentrated velocity flow are major causes of slope problems and may trigger landslides.

Changes in Vegetation
Removing vegetation from very steep slopes can increase landslide hazards. Areas that have experienced wildfire and land clearing for development may experience long periods of increased landslide hazard.

In addition, woody debris in stream channels (both natural and man-made from logging) may cause the impacts from debris flows to be more severe.

LANDSLIDE MANAGEMENT
While small landslides are frequently a result of human activity, the largest landslides are often naturally occurring phenomena with little or no human contribution. The sites of large landslides are typically areas of previous landslide movement that are periodically reactivated by significant precipitation or seismic events. These naturally occurring landslides can disrupt roadways and other infrastructure lifelines, destroy private property, and cause flooding, bank erosion, and rapid channel migration .

Landslides can create immediate, critical threats to public safety. Engineering solutions to protect structures on or adjacent to large active landslides are often extremely or prohibitively expensive. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 205

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In spite of their destructive potential, landslides can serve beneficial functions to the natural environment.

They supply sediment and large wood to the channel network and can contribute to complexity and dynamic channel behavior critical for aquatic and riparian ecological diversity. Effective landslide management should include the following elements:
• Continuing investigation to identify natural landslides, understand their mechanics, assess their risk to public health and welfare, and understand their role in ecological systems. • Regulation of development in or near existing landslides or areas of natural instability through the Santa Clara County Code and City ordinances. • Preparation for emergency response to landslides to facilitate rapid, coordinated action among Santa Clara County, local cities, and state and federal agencies, and to provide emergency assistance to affected or at-risk citizens.
• Evaluation of options including landslide stabilization or structure relocation where landslides are identified that threaten critical public structures or infrastructure.

LAND SUBSIDENCE EFFECTS
Subsidence is one of the most diverse forms of ground failure, ranging from small or local collapses to broad regional lowering of the earth's surface. The causes of subsidence, mostly associated with human activities, are as diverse as the forms of failure, and include dewatering (oxidation) of peat or organic soils, dissolution in limestone aquifers, first-time wetting of moisture-deficient low-density soils, natural compaction, liquefaction, crustal deformation, subterranean mining, and withdrawal of fluids (groundwater, petroleum, geothermal).

The compaction of susceptible aquifer systems caused by excessive groundwater pumping is the single largest cause of subsidence in California, and the 5,200 square miles affected by subsidence in the San Joaquin Valley since the latter half of the 20th century has been identified as the single largest human alteration of the Earth's surface topography. The second largest cause of subsidence in California is the oxidation (decomposition) of organic soils (USGS, 2017c).

Aquifer Compaction
Aquifer compaction due to groundwater pumping affects both manmade infrastructures and natural systems. The greatest effects are on infrastructure that traverses a subsiding area. In the San Joaquin Valley, the main problems reported are related to water conveyance structures. Many water conveyance structures, including long stretches of the California Aqueduct, are gravity driven through the use of very small gradients; even minor changes in these gradients can cause reductions in designed flow capacity. Managers of the canals, such as the California Department of Water Resources, the San Luis Delta-Mendota Authority, the Bureau of Reclamation, and the Central California Irrigation District, have to repeatedly retrofit their canals to keep the water flowing, even at reduced amounts. Subsidence also affects roads, railways, bridges, pipelines, buildings, and wells.

Compaction of an aquifer system may permanently decrease the aquifer's capacity to store water. Even when water levels rise, sediments can remain compacted; most compaction that occurs as a result of historically low groundwater levels is irreversible.

Additionally, as the topography of the land changes by varying amounts in different places, low areas, such as wetlands, change size and shape, migrate to lower elevations, or even disappear. Rivers may change course or erosion/ deposition patterns to reach a new equilibrium. 206 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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Decomposition of Wetland Solis
The Sacramento-San Joaquin Delta of California was once a great tidal freshwater marsh. It is blanketed by peat and peaty alluvium deposited where streams that originate in the Sierra Nevada, Coast Ranges, and South Cascade Range enter San Francisco Bay. In the late 1800s, lev es were built along the sb'eam channels, and the land thus protected from flooding was drained, cleared, and planted. The leveed tracts and islands help to protect water-export facilities in the southern Delta from saltwater intrusion by displacing water and maintaining favorable freshwater gradients, However, The decomposition of organic carbon in the peat soils causes land subsidence in the Delta and increases stresses on the levees.

Ongoing subsidence behind the levees, w11ere the land has been drained, exposed to the atmosphere, and planted, increases stresses on the levee system, making it less stable. This threatens to damage agricultural and developed lands and degrade water quality in the massive water-transfer system.

HAZARD PROFILE

PAST EVENTS
Losses from landslides are typically lower than those from flooding. However, in the EI Nino storms of eal'ly 1998, the USGS documented $150 million in losses due to approximately 300 landslides in the Bay Area and Santa Clara County. The slides ranged from a 25-cubic-meter failure of engineered material to reactivation of the 13 million-cubic-meter Mission Peak earth flow complex in Alameda County, Landslides have occurred in conjunction with earthquakes and heavy rains events in Santa Clara County.

Table 10-11ists known landslide events that affected Santa Clara County between 1980 and 2016. Two other landslides outside of Santa Clara County are also recorded in USGS archives. One occurred in 2012 and the other in 1970; both were about an hour's drive from the County but still near the Bay Area.

TABLE 10-1. LANDSLIDE EVENTS IN SANTA CLARA COUNTY

I IFEMA
Dates of Event I Event Type I Declar Location Losses/Impacts , atlon
12/19/1981 to Severe storms, flood, 651
1/0811982 mudslides, high tide
S F . Prolonged heavy rains and saturated soils caused numerous an ranclsco . B slope failures and mud flows on steep and unstable slopes ay area throughout the San Francisco Bay area.
1/21/1983 to Coastal storms, floods, slides, 677
3/30/1983 tornadoes
SF ' A landslide restricted Clayton Road to one lane just east of the Ban ranclsco community of Alum Rock. Another, on the east side of Milpitas, ayarea resulted In vertical and horizontal offset of a roadway. 4/24/1984 Morgan Hill Earthquake
Calaveras fault Th' 6 2 't d rth k d' I d I'd east of San IS. magnl u ~ ea qua e cause minor an s I es I J ' throughout the region. ose. - - -
San Andreas Landslides and rockslides in Santa Clara County on steep 10/17/1989 Lorna Prieta Earthquake 845 fault near slopes in the Santa Cruz Mountains blocked roads, damaged Lorna Prieta. structures, and caused at least two deaths. 1/0311995 to Severe winter storms, flooding, 1044
2/10/1995 landslides, mud flows
San Francisco Minor landslide damage in Santa Clara County was attributed to Bay area heavy rains and saturated soils.
2/13/1995 to Severe winter storms, flooding, 1046
4/19/1995 landslides, mud flows
San Francisco Minor landslide damage in Santa Clara County was attributed to Bay area heavy rains and saturated soils.
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FEMA I I
Dates of Event I Event Type Declar Location I Losses/Impacts I : atlon
$7.6 million in Santa Clara County landslide damage occurred I
I mostly in the northern county. along the range front of the Santa Clara Valley. $6.1 million in damage was attributed to
reactivation of three local landslides. The rest was attributed to 2/02/1998 to S~vere ~inter Storms and EI 1203 San Francisco small debris flows along road cuts or narrow canyon walls. In 4/30/1998 NinO Rainstorm Bay region Alum Rock. the Penitencia Creek landslide caused extensive damage to water and sewer lines and closed roads. Another landslide closed Clayton Road east of Alum Rock area. The third. near Old Piedmont Road on the east side of Milpitas, had I a displacement near the toe of about 20 cm.

Sources: ABAG, 2010; USGS 1984, 1987, 1989 and 1998; NOAA, 2017 According to the Santa Clara Valley Water District (SCVWD), Santa Clara County has experienced as much as 13 feet of subsidence caused by excessive pumping of groundwater in the early 1900s. The SCVWD was created in the early 1930s to protect groundwater resources and minimize land subsidence.

To reduce the demand on groundwater and minimize subsidence, the SCVWD uses a combination of imported surface water (from the State Water Project and San Francisco's Hetch-Hetchy system) and groundwater. Figure 10-6 shows the history of land surface elevation, groundwater elevation, and the population of Santa Clara County from 1900 up to 2020. The SCVWD started importing water in the 19605 when the groundwater elevation reached its lowest elevation. 208 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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r - - ~ - ~
.. Land Surla~!I' El8vati~n
HlVATION
.'(1 ---
ICUil
YeG!" wd! .•
~~i"'·« ~\lCllldfC
t'1~~_II. "U;w'_ I~. '"I wcMI
• c!t .•
G roundwote-r Elevation
F nl dt4I\1of;flf1 "I
1"" ... Iod ... _ I~t~
-eft· • • •••
. ; .

Source: SCVWD, 2016b
II. 'I
0«Jf fl)O YfXlrS, r~ wafer dls/rler's worer Importarlon ofrd groundwam mono90mant ocIN/ffo, have stabilIzed groundwamr leval, and prevented land subsidence. Of 5inking.

FIGURE 10-6. SCVWD TrM ELINE OF WATER IMPORTATION AND GROUNDWATER M ANAGEMENT

LOCATION
In general, landslid e hazard areas are where the land has characteristics that contribute to the risk of the downhill movement of material, such as the following:
• A slope greater than 33 percent.
• A history of landslide activity or movement during the last 10,000 years. • Stream or wave activity, which has caused erosion, undercut a bank or cut into a bank to cause the surrounding land to be unstable.
• The presence of an alluvial fan, indicating vulnerability to the flow of debris or sediments. • The presence of impermeable soils, such as silt or clay, which are mixed with granular soils such as sand and gravel.

The best available predictor of where movement of slides and earth flows might occur is the location of past movements. Past landslides can be recognized by their distinctive topographic shapes, which can remain in place for thousands of years. Most landslides recognizable in this fashion range from a few acres to several square miles. Most show no evidence of recent movement and are not currently active.

A small proportion of them may become active in any given year, with movements concentrated within all or part of the landslide masses or around their edges. 'fhe recognition of ancient dormant mass movement sites is important in the identification of areas susceptible to flows and slides because they can be reactivated by earthquakes or by exceptionally wet 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 209

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weather. Also, because they consist of broken materials and frequently involve disruption of groundwater flow, these dormant sites are vulnerable to construction-triggered sliding.

The California Landslide Hazard Identification Act directs the State Geologist to identify and map hazardous landslide areas for use by municipalities in planning and decision-making on grading and building permits. Three factors that characterize landslide hazard areas include significant slope, weak rocks, and heavy rains. This program focuses on urban areas and growth areas that exhibit these characteristics. Although the California Geological Survey provides access to many of these maps through its California Landslide Inventory, it does not offer them at the County level for Santa Clara County (California Geological Survey, 2016).

The Association of Bay Area Governments Resilience Program provides more detailed mapping for the Bay Area through use of USGS Summary of Distribution of Slides and Earth Flaws (1997) and Map Shawing Principal Debris-Flaw Source Areas (1997). The County of Santa Clara overlaid these data on its jurisdictional boundaries to develop
Error! Reference source not found .. As shown, the OA includes both high- and low-risk landslide areas.

FREQUENCY
Landslides are often triggered by other natural hazards such as earthquakes, heavy rain, floods or wildfires, so landslide frequency is often related to the frequency of these other hazards. In the OA, landslides typically occur where landslides and earth flows have occurred in the past. These previous locations may not show any evidence of recent movement and may not be currently active, but some portion of them may become active in any given year from natural hazard events. As shown in Table 10-1, damage from the EI Nino rainstorm event in 1998 was mainly attributed to reactivation of landslide locations and because of sequential severe storms that saturated steep, vulnerable soils. Landslide events occurred during the severe storms of 1983,1995, and 1998. Until better data is generated specifically for landslide hazards, this severe storm frequency is appropriate for the purpose of ranking risk associated with the landslide hazard.

SEVERITY
Landslides destroy property and infrastructure and can take the lives of people. Slope failures in the United States result in an average of 25 lives lost per year and an annual cost to society of about $1.5 billion. Landslides can pose a serious hazard to properties on or below hillsides. When landslides occur - in response to such changes as increased water content, earthquake shaking, addition of load, or removal of downslope support - they deform and tilt the ground surface. The result can be destruction of foundations, offset of roads, breaking of underground pipes, or overriding of downslope property and structures.
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WARNING TIME
The speed of mass movements may range from inches per year to many feet per second, depending on slope, material and water content . Some monitoring methods can provide an idea of the type of movement and the amount of time prior to failure. It is also possible to determine what areas are at risk during general time periods. Assessing geology, vegetation and predicted precipitation can help in predictions. However, there is no practical warning system for individual landslides. The current standard operating procedure is to monitor situations case-by-case and respond after the event has occurred. Warning signs for landslide activity include the following:
• Springs, seeps, or saturated ground in areas that have not typically been wet before. • New cracks or unusual bulges in the ground, street pavements or sidewalks. • Soil moving away from foundations.
• Ancillary structures such as decks and patios tilting and/ or moving relative to the main house. • Tilting or cracking of concrete floors and foundations. • Broken water lines and other underground utilities.
• Leaning telephone poles, trees, retaining walls or fences. • Offset fence lines.
• Sunken or down-dropped road beds.
• Rapid increase in creek water levels, possibly accompanied by increased turbidity (soil content).
• Sudden decrease in creek water levels though rain is still falling or just recently stopped. • Sticking doors and windows, and visible open spaces indicating jambs and frames out of plumb.
• A faint rumbling sound that increases in volume as the landslide nears. • Unusual sounds, such as trees cracking or boulders knocking together.

SECONDARY HAZARDS
Landslides can cause secondary effects such as blocking access to roads, which can isolate residents and businesses and delay transportation. This could resu lt in economic losses for businesses. Other potential problems resulting from landslides are power and communication failures. Vegetation or poles on slopes can be knocked over, resulting in possible losses to power and communication lines. Landslides also have the potential of destabilizing the foundation of structures, which may result in monetary loss for residents. They also can damage rivers or streams, potentially harming water quality, fisheries and spawning habitat.

EXPOSURE

POPULATION
Population could not be examined by landslide hazard area because the boundaries of census block groups do not coincide with the hazard al'ea boundaries. However, population was estimated using 'the residential building count in each mapped hazard area and multiplying by the 2016 estimated average popUlation per household. Using this approach, the estimated population living in the "moderate landslides" risk area is 46,397, "high landslide" risk area is 113,137 and "very high landslide" risk area is 5,399.
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PROPERTY

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There are 28,196 structures on parcels in the high landslide risk areas, with an estimated value of $27 billion. Table 10-2, Table 10-3, and Table 10-4 show the number and replacement value of structures exposed to the landslide risk. Over 96 percent of the exposed structures are dwellings. Table 10-5 shows the general land use of parcels exposed to moderate, high and very high landslide hazard in unincorporated portions of the OA. Lands zoned for agricultural uses are most vulnerable.

TABLE 10-2. EXPOSURE AND VALUE OF STRUCTURES IN MODERATE LANDSLIDE RISK AREAS JUrisdiction I Esllm_ated Val~e wl!!:lIn the La~sllde B'~I % of Total Replacement Structure Contents Total Value
Campbell $3,121,464 $1,560,732 $4,682,197 0.04%
Cupertino $190,106,812 $95,053,406 $285,160,218 2.05%
Gilroy $101,070,569 $52,408,387 $153,478,956 '1.15%
Los Altos $264,701,185 $179,480,420 $444,181,605 5.03%
Los Altos Hills $803,549,564 $472,373,076 $1,275,922,640 39.35% Los Gatos $933,001,058 $673,980.710 $1,606,981,768 14.75% Milpitas $24,758,577 $13,689,330 $38,447,907 10.20%
Monte Sereno $234,411,610 $117 ,205,805 $351,617,415 140.28% Morgan Hill $191,890,675 $99,229,710 ' $291,120,385 !2.61% Mountain View $0 $0 $0 0.00%
Palo Alto $751,245,482 $956,455,304 $1,707,700,785 i6.62% San Jose $2,036,605,070 $1 ,142,138,929 $3,178,743,999 1.49% Santa Cla.ra (city) $0 $0 $0 '0.00%
Saratoga $547,819,024 $323,476,706 $871,295,730 ' 10.70% Sunnyvale $0 $0 $0 iO.OO%
Unincorporated County $1 ,157,206,472 $784,286,519 $1 ,941,492,991 7.66% ToOO $7J d Dl4 ..... 2.65%
TABLE 10-3. EXPOSURE AND V ALUE OF STRUCTURES IN HIGH LANDSLIDE RISK AREAS JUrisdiction I Estimated _Val!:!.e WI~hln J!.~ Landslide BLsk Area ___ % of Total Replacement Structure Contents Total ,ValLie
Campbell $217,596,648 '$200,013,738 $417,610,386 3.73%
Cupertino $574,790,476 $314,896,921 $889,687,397 6.40%
Gilroy $377,351,372 $206,965,219 $584,316,591 4.36%
Los Altos $205,378,603 $133,164,941 $338,543,544 '3.84% Los Altos Hills $_645,1 59,815 $379,839,286 $1,024,999,101 31.61% Los Gatos $1 ,521,396,089 $1 ,020,1 05,580 $2,541,501,669 23.33% Milpitas $249,861,269 : $127,1 01 ,096 $376,962,365 1.97% Monte Sereno $92,128,893 $46,064,447 $138,193,340 15.83% Morgan Hill $553,617,617 1$284,963,481 $838,581,098 17.51 % Mountain View $32,403,360 $16,201,680 $48,605,041 '0.19% Palo Alto $329,836,716 $348,824,560 $~78,661,276 '2.63% San Jose $5,821,965,628 $3,605,488,466 $9,427,454,094 4.42% Santa Clara !cit~l $61.122,866 $34,772,456 $95895,321 0.22% 212 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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Estimated Value within the Landslide Risk Area I % of Total Replacement JUrisdiction - ----- - -- - ---- Saratoga
Sunnyvale
Unincor orated County
Total
Structure Contents Total I Value
$1,310,161,174
$114,604,443
1$838,992,857
$91,046,922
$3,457,377,079
$111O'S 818 729
TABLE 10-4. EXPOSURE AND VALUE OF STRUCTURES IN VERY HIGH LANDSLIDE RISK AREAS Estimated Value within the Landslide Risk Area 1% of Total Replacement JUrisdiction - - , Structure Contents Total Value
Campbell $3,818,063 $4,993,432 $8,811,495 0.08%
Cupertino $27,999,100 $13,999,550 $41,998,650 0.30%
Gilroy $4,905,422 $2,452,711 $7,358,133 0.05%
Los Altos $0 $0 $0 0.00%
Los Altos Hills $8,007,971 $4,003,986 $12,011,957 0.37% Los Gatos $71 ,791,878 $50.946,143 $122,738,022 1.13%
Milpitas $10,633)625 $7,189,915 $17,823,539 0.09%
Monte Sereno $1 ,755,292 $877,646 $2,632,937 0.30%
Morgan Hili $41 ,830,817 $20,915,409 $62,746,226 0.56%
Mountain View $0 $0 $0 0.00%
Palo Alto $0 $0 $0 0.00%
San Jose $78,112,632 $48,583,546 $126,696,178 0.06%
Santa Clara (city) $0 $0 0.00%
Saratoga $46,507,153 $123,359,847 1.51%
Sunnyvale $0 $0 0.00%
Unincorporated County $819,337,451 $1 ,754,353,841 6.92% Total $1,0198089'1 52.280,530,828 G.48%
TABLE 10-5. LAND USE IN LANDSLIDE HAZARD AREAS
I Mode rate High Very HI ~
T pe of Land Use I A re~- % of total- - Area acre s I % of total Area-;cres ! % o~ Agricultural 2,575.4 1.46 1,025.6 0.38 150.2 0.36
General/Institutional 519.6 0.30 200.9 0.07 29.5 0.07
Open Space 169,535.7 96.28 1268,021 .3 98.91 41 ,357.9 98.16 Low Density Residential 3,275.8 1.86 1,573.2 0.58 435.0 1.03 High Density Residential 14.3 0.01 2.9 0.00 0.0 0.00
Commercial 161.8 0.09 161.8 0.38
Industrial 0.9 0.00
Total 178083.5 \l(6Wo

CRITICAL FACILITIES AND INFRASTRUCTURE
Table 10-6, Table 10-7, and Table 10-8 summarizes critical facilities exposed to the landslide hazard in moderate, high, and very high risk areas. No loss estimation of these facilities was performed due to the lack of established damage functions for the landslide hazard. A significant amount of infrastructure, under the Infrastructure Lifeline category, can be exposed to mass movements:
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• Roads - Access to major roads is crucial after a disaster event. Landslides can block roads, causing neighborhood isolation and transportation delays. This can result in economic losses for businesses.
• Bridges - Landslides can damage road bridges. Mass movements can knock out bridge abutments or significantly weaken the soil supporting them, making them hazardous for use. • Power Lines - Power lines are generally elevated above steep slopes; but the towers supporting them can be subject to landslides. A landslide could trigger failure of the soil underneath a tower, causing it to collapse and ripping down the lines.

TABLE 10-6. CRITICAL FACILITIES AND INFRASTRUCTURE IN MODERATE LANDSLIDE RISK AREAS J d" t R I P bl Infrastructure Military Recovery Socioeconomic Hazardous Ttl ~~Mq " I uns Ie Ion H::f.~n;~afet u IC ' Llfeline Facilities Facilities Facilities Malenals 0 a Cupertino 1 0 0 :0 0 0 1
Gilroy .0 0 0 iO i 2 0 2
Los Altos 0 0 0 '0 2 0 2
Los Altos Hills 0 9 0 iO 3 0 12
Los Gatos 0 0 '0 0 0 1
Milpitas 0 1 0 10 0 0 1
Monte Sereno 0 1 0 0 1 0 2
Morgan Hill 0 0 0 !O 0 0 0
Mountain View 0 0 0 0 0 0 0
Palo Alto 0 0 0 io 0 3 3
San Jose 2 8 0 0 5 0 16
Santa Clara (city) 0 0 0 ,0 0 0 0
Saratoga 0 0 0 0 0 1
Sunnyvale 0 0 0 io 0 0 0
Unincorporated County 1 21 0 '0 2 0 24
T'Ota) S 42 0- 0 15 3 65
TABLE 10-7. CRITICAL FACILITIES AND INFRASTRUCTURE IN HIGH LANDSLIDE RISK AREAS I
I I I Emer enc
J d t R 9 YIP bl Infrastructure! MIlitary Recovery Socioeconomic Hazardous Ttl UriS Ie Ion esponse U IC 0 a Health & Safe! Lifeline I Facilities Facilities I FaCilities Matenals ,
Cupertino 0 8 0 0 2 1 t1
Gilroy 0 3 0 0 0 0
Los Altos 0 14 0 0 1 0
Los Altos Hills 15 0 0 0 0
Los Gatos 1 12 0 0 5 0
Milpitas 0 3 0 0 0 0
Monte Sereno 0 1 0 0 0 0
Morgan Hili 2 0 0 0 5 0
Mountain View 0 4 0 0 0 0
Palo Alto 0 9 0 0 0 0
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San Jose ;4 108 0 0 10 123
S~nta Cla!a (city) 10 8 0 0 0 0 8
Sar!ltoga ,1 10 0 cO 2 0 1~
Sunnyva.l_e 10 2 0 0 0 3
Unincorporated County 5 71 0 0 8 1 85
ota' 14 277 0 0 34 3 328
TABLE 10-8. CRITICAL FACILITIES AND INFRASTRUCTURE IN VERY HIGH LANDSLIDE RISK AREAS Cupertino 0 0 0 0
Gilroy :0 0 0 0 0 0
Los Altos :0 0 0 0 0 0
Los Altos Hills 0 0 0 0 10 0
Los Gatos '0 0 0 0 0 0 0
Milpitas 0 0 0 0 0 0 0
Monte Sereno 0 0 0 0 0 0 0
Morgan (:1111 0 0 0 0 ,0 0 0
Mountain View 0 0 0 ,0 0 0 0 .-
Palo Alto 0 0 0 ,0 10 0 0
San Jose 0 0 0 '0 0 1
Santa Clara (city) 0 0 0 0 0 0 0
Saratoga '0 0 0 0 0 0 0
Sunnyvale 0 0 0 ,0 '0 0 0
Unincorporated County 0 14 0 10 0 0 4
5 0 0 0 5

ENVIRONMENT
Environmental problems as a result of mass movements can be numerous . Landslides that fall into streams may significantly impact fish and wildlife habitat, as well as affecting water quality. Hillsides that provide wildlife habitat can be lost for prolong periods of time due to landslides.

VULNERABILITY

POPULATION
All of the estimated 113,137 persons exposed to high landslide risk areas are considered to be vulnerable.

Increasing population and the fact that many homes are built on view property atop or below bluffs and on steep slopes subject to mass movement, increases the number of lives endangered by this hazard.

PROPERTY
Although complete historical documentation of the landslide threat in the OA is lacking, the mountainous terrain surrounding the Santa Clara Valley indicates potential for landslides. Loss estimations for the landslide hazard are not based on modeling utilizing damage functions, because no 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 215

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such damage functions have been generated. Instead, loss estimates were developed representing 10 percent, 30 percent and 50 percent of the replacement value of exposed structures. This allows emergency managers to select a range of economic impact based on an estimate of the percent of damage to the general building stock. Damage in excess of 50 percent is considered to be substantial by most building codes and typically requires total reconstruction of the structure. Table 10-9 shows the general building stock loss estimates in the aggregate of all landslide risk areas.

Campbell $431,104,078 43,110,408 129,331,223 215,552,039 Cupertino $1,216,846,265 121,684,627 365,053,880 608,423,133 Gilroy $745,153,680 74,515.368 ! 223,546,104 372,576,840 Los Altos $782,725,150 78,272,515 234,817,545 391,362,575 Los Altos Hills $2,312,933,698 231,293,370 : 693,880,110 1,156,466,849 Los Gatos $4,271,221,458 427,122,146 1,281,366,437 2,135,610,729 Milpitas $433,233,811 43,323,381 : 129,970,143 216,616,906 Monte Sereno $492,443,692 49,244,369 ' 147,733,108 246,221,846 Morgan Hill $1,192,447,709 119,244,771 357,734,313 596,223,855 Mountain View $48,605,041 4,860,504 : 14,581,512 24,302,520 Palo Alto $2,386,362,061 238,636,206 715,908,618 1,193,181,030 San Jose $12 , 732 . 894 .~ 71 1,273,289,427 3,819,868,281 6,366,447,135 Santa Clara (city) $95.895.321 9,589,532 28,768,596 47,947,661 Saratoga $3,143,809,608 314,380,961 943,142,882 1.571,904,804 Sunnyvale $205,651.365 20,565,137 61,695,410 102,825,683 Unincorporated Coun $431,104,078 43,110,408 129,331,223 215,552,039 Totti $30 491.327{209 3049132721 9.147398183 15245 663604

CRITICAL FACILITIES AND INFRASTRUCTURE
There are 398 critical facilities exposed to the landslide hazard to some degree. A more in-depth analysis of the mitigation measures taken by these facilities to prevent damage from mass movements should be done to determine if they could withstand impacts of a mass movement.

Several types of infrastructure are exposed to mass movements, including transportation, water and sewer and power infrastructure. Highly susceptible areas of the OA include mountain roads and transportation infrastructure. At this time all infrastructure and transportation corridors identified as exposed to the landslide hazard are considered vulnerable until more information becomes available.

ENVIRONMENT
The environment vulnerable to landslide hazard is the same as the environment exposed to the hazard.

FUTURE TRENDS IN DEVELOPMENT
Santa Clara County has been one of the state's fastest growing counties over the past 10 years, averaging a 1.21-percent increase in population per year from 2005 through 2015. The planning partners are equipped to handle future growth within landslide hazard areas. Landslide risk areas are addressed in 216 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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the safety elements of local general plans . All planning partners have committed to linking their general plans to this hazard mitigation plan. This will create an opportunity for wise land use decisions as future growth impacts landslide hazard areas.

Additionally, the State of California has adopted the International Building Code (!BC) by reference in its California Building Standards Code. The !BC includes provisions for geotechnical analyses in steep slope areas that have soil types considered susceptible to landslide hazards. These provisions assure that new construction is built to standards that reduce the vulnerability to landslide risk.

SCENARIO
Major landslides in the OA occur as a result of reactivation of previous landslides and soil conditions that have been affected by severe storms, groundwater or human development. The worst-case scenario for landslide hazards in the OA would generally correspond to a severe storm that had heavy rain and caused flooding. Landslides are most likely during late winter when the water table is high. After heavy rains from November to December, soils become saturated with water. As water seeps downward through upper soils that may consist of permeable sands and gravels and accumulates on impermeable silt, it will cause weakness and destabilization in the slope. A short intense storm could cause saturated soil to move, resulting in landslides. As rains continue, the groundwater table rises, adding to the weakening of the slope. Gravity, poor drainage, a rising groundwater table and poor soil exacerbate hazardous conditions.

Mass movements are becoming more of a concern as development moves outside of urban centers and into areas less developed in terms of infrastructure. Most mass movements would be isolated events affecting specific areas. It is probable that private and public property, induding infrastructure, will be affected. Mass movements could affect bridges that pass over landslide prone ravines and knock out rail service through the OA. Road obstructions caused by mass movements would create isolation problems for residents and businesses in sparsely developed areas. Property owners exposed to steep slopes may suffer damage to property or structures. Landslides carrying vegetation such as shrubs and trees may cause a break in utility lines, cutting off power and communication access to residents.

Continued heavy rains and flooding will complicate the problem further. As emergency response resources are applied to problems with flooding, it is possible they will be unavailable to assist with landslides occurring all over the OA.

ISSUES
Important issues associated with landslides in the OA include the following:
• There are existing homes in landslide risk areas throughout the OA. The degree of vulnerability of these structures depends on the codes and standards the structures were constructed to. Information to this level of detail is not currently available. • Future development could lead to more homes in landslide risk areas. • Mapping and assessment of landslide hazards are constantly evolving. As new data and science become available, assessments of landslide risk should be reevaluated. • The impact of climate change on landslides is uncertain. If climate change impacts atmospheric conditions, then exposure to landslide risks is likely to increase. • Landslides may cause negative environmental consequences, including water quality degradation.
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• The risk associated with the landslide hazard overlaps the risk associated with other hazards such as earthquake, flood and wildfire. This provides an opportunity to seek mitigation alternatives with multiple objectives that can reduce risk for multiple hazards. 218 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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SEVERE WEATHER

GENERAL BACKGROUND
Severe weather refers to any dangerous meteorological phenomena with the potential to cause damage, serious social disruption, or loss of human life. Severe weather can be categorized into two groups:
systems that form over wide geographic areas are classified as general severe weather; those with a more limited geographic area are classified as localized severe weather. Severe weather, technically, is not the same as extreme weather, which refers to unusual
weather events at the extremes of the historical DEFINITIONS distribution for a given area.

The most common severe weather events that impact
the Santa Clara County OA are heavy
rains/ atmosph eric rivers, extreme temp eratur es, high wind, and spac e weath er. Exb'eme cold weather has
not been profiled for the Santa Clara County OA has
its frequenc y and severity do not warrant assessment
(the California State Hazard Mitigation Plan also
omitted extrem e cold weather as an identified hazard
of concern). These types of severe weather are
described in the following sections. Flooding issues
associated with severe weather are discussed in
Chapter O.

HEAVY RAIN/ATMOSPHERIC RIVER
Most severe storms in the Santa Clara County OA
consist of atmospheric rivers, heavy rains or
thunderstorms. Heavy rain refers to events where the
amount of rain exceeds normal levels. The amount of
precipitation needed to qualify as heavy rain varies
with location and season , Heavy rain is distinct from
climate change analyses on increasing predpitatiol1. It does not mean that the total amount of precipitation at a location has increased, just that the rain is occurring in a more intense event. More frequent heavy rain
events, however, can serve as indicators of changing
precipitation levels. Heavy rain is most frequently
Atmospheric Rlver-A long, narrow region in the
atmosphere that transports most of the water vapor
outSide of the tropiCS. These cOlumns of vapor move
with the weather, carrying large amounts of water vapor and strong winds. When atmospheric rivers make
landfall, they releas.e this vC!por in the form of rain or snow, causing flooding and mudslide vents.

Extreme Cold-Temperatures that are below normal
that may lead to serious health problems. Extreme cold
is a dangerous situation that can bring on health
emergencies.

Extreme Heat- Temperatures that hover H)OF or more
above the avera.ge high temperature for a region and
last for several Weeks. Humid or m uggy conditions
occur when a "dome" of high atmospheric pressure
traps hazy, damp air near the ground. Extremely dry
and hot conditions can provoke dust storms and low
visibility.

Severe Local Storm-Small atmospheriC systems,
including tornadoes, thunderstorms, windstorms, ice
storms and snowstorms. Typically, major impacts from
a severe storm are on transportation infrastructure and utilities. These storms may cause a great deal of
destruction and even death, but their impact is
genel'ally confined to a small area.

Space Weather-Variations in the space environment
betwe:en the sun and earth. It can influence the
p~rfQr:mance of technology used on Earth.

Wlndstonn-A storm featuring violent winds.

Wind.st<!lm"(s are generally short-duration events
Involving straight-line winds or gusts of over 50 mph,
strong enol.!Qh to cause property damage.
measured by tracking the frequency of events, analyzing the mean return period, and measuring the amount of precipitation in a certain period (most typically inches of rain within a 24-hour period) (EPA, 2015).

A relatively common weather pattern that brings southwest winds and heavy rain to California is often referred to as an atmospheriC river. Atmospheric rivers are long, narrow Tegions in the atmosphere that transport most of the water vapor carried away from the tropics. These columns of vapor move with the weather, carrying large amounts of water vapor and strong winds . When the atmospheric rivers make landfall, they often release this water vapor in the form of rain or snow, causingilooding and mudslide vents.
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A thunderstorm is a rain event that includes thunder and lightning. A thunderstorm is classified as "severe" when it contains one or more of the following: hail with a diameter of three-quarter inch or greater, winds gusting in excess of 50 knots (57.5 mph), or tornado.

Three factors cause thunderstorms to form: moisture, rising unstable air (air that keeps rising when disturbed), and a lifting mechanism to provide the disturbance. The sun heats the surface of the earth, which warms the air above it. If this warm surface air is forced to rise (hills or mountains can cause rising motion, as can the interaction of warm air and cold air or wet air and dry air) it will continue to rise as long as it weighs less and stays warmer than the air around it. As the air rises, it transfers heat from the surface of the earth to the upper levels of the atmosphere (the process of convection). The water vapor it contains begins to cool and it condenses into a cloud. The cloud eventually grows upward into areas where the temperature is below freezing. Some of the water vapor turns to ice and some of it tums into water droplets. Both have electrical charges. Ice particles usually have positiv e charges, and rain droplets usually hav e negative charges. When the charges build up enough, they are discharged in a bolt of lightning, which causes the sound waves we hear as thunder. Thunderstorms have three stages (see Figure 11-1):
• The developing stage of a thunderstorm is marked by a cumulus cloud that is being pushed upward by a rising column of air (updraft). The cumulus cloud soon looks like a tower (called towering cumulus) as the updraft continues to develop. There is little to no rain during this stage but occasional lightning. The developing stage lasts about 10 minutes. • The thunderstorm enters the mature stage when the updraft continues to feed the storm, but precipitation begins to fall out of the storm, and a downdraft begins (a column of air pushing downward). When the downdraft and rain-cooled air spread out along the ground, they form a gust front, or a line of gusty winds. The mature stage is the most likely time for hail, heavy rain, frequent lightning, strong winds, and tornadoes. The storm occasionally has a black or dark green appearance.
• Eventually, a large amount of precipitation is produced and the updraft is overcome by the downdraft beginning the dissipating stage. At the ground, the gust front moves out a long distanc e from the storm and cuts off the warm moist air that was feeding the tllUnderstor m.

Rainfall decreases in intensity, but lightning remains a danger.

Source: NOAA, 2015
-30
I I I I' I -20
6 IJ JJ i I
-10
4 0
10 2
FIGURE 11-1. THE THUNDERSTORM LIFE CYCLE
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There are four types of thunderstorms:
• Single-Cell Thunderstorms-Single-cell thunderstorms usually last 20 to 30 minutes. A true single-cell storm is rare, because the gust front of one cell often triggers the growth of another.

Most single-cell storms are not usually severe, but a single-cell storm can produce a brief severe weather event. When this happens, it is called a pulse severe storm. • Multi-Cell Cluster Storm - A multi-cell cluster is the most common type of thunderstorm. It consists of a group of cells, moving as one unit, with each cell in a different phase of the thunderstorm life cycle. It is usually more intense than a single cell storm. Mature cells are usually at the center of the cluster and dissipating cells at the downwind edge. These storms can produce moderate-size hail, flash floods and weak tornadoes. Each cell lasts only about 20 minutes, but the cluster may persist for several hours. • Multi-Cell Squall Line - A multi-cell line storm, or squall line, consists of a long line of storms with a continuous well-developed gust front at the leading edge. The line of storms can be solid, or there can be gaps and breaks in the line. Squall lines can produce hail up to golf-ball size, heavy rainfall, and weak tornadoes, but they are best known as the producers of strong downdrafts. Occasionally, a strong downburst will accelerate a portion of the squall line ahead of the rest of the line. This produces what is called a bow echo. Bow echoes can develop with isolated cells as well as squall lines. Bow echoes are easily detected on radar but are difficult to observe visually.
• Super-Cell Storm - A super-cell is a highly organized thunderstorm. It is similar to a single­ cell storm in that it has one main updraft, but the updraft is extremely strong, reaching speeds of 150 to 175 miles per hour. Super-cells are rare . The main characteristic that sets them apart from other thunderstorms is the presence of rotation. The rotating updraft of a super-cell (called a mesocyclone when visible on radar) helps the super-cell to produce extreme weather events, such as giant hail (more than 2 inches in diameter), strong downbursts of 80 miles an hour or more, and strong to violent tornadoes.

NOAA classifies a thunderstorm as a storm with lightning and thunder produced by cumulonimbus clouds, usually producing gusty winds, heavy rain, and sometimes hail. Thunderstorms are usually short in duration (seldom more than two hours). Heavy rains associated with thunderstorms can lead to flash flooding during the wet or dry season. According to the American Meteorological Society Glossary of Meteorology, thunderstorms are reported as light, medium, or heavy according to the following characteristics :
• Nature of the lightning and thunder .
• Type and intensity of the precipitation, if any.
• Speed and gustiness of the wind.
• Appearance of the clouds.
• Effect on surface temperature.

EXTREME TEMPERATURES
Extreme temperatures are unexpected, unusual, or unseasonal temperatures-cold or hot-that can create dangerous situations. Extreme cold temperatures are below normal temperatures that may lead to serious health problems. Exposure to the extreme cold can lead to hypothermia and frostbite in people exposed to the weather without adequate clothing protection. It may result in death if it exacerbates preexisting chronic conditions.
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Extreme heat is defined as temperatures that hover 10°F or more above the average high temperatures for the region for several weeks. Ambient air temperature and relative humidity are components of heat conditions, together defining the "apparent temperature," as shown in Figure 11-2. Extreme heat is the primary weather-related cause of death in the U.s. In a 30-year average of weather fatalities across the nation from 1986-2015, excessive heat claimed more lives each year than floods, lightning, tornadoes, and hurricanes. In 2015, heat claimed 45 lives, though none of them were in California (NWS, 2016b).

Source: NWS. 2016
NWS Heat Index Temperature (OF)
40 83
45 84 87
-'#. 60 85 88
->- 66 81 84 86 89 :!:!
60 82 84 ' 88 91 :2
E 65 82 85 89 93
= ~ 70 83 86 90 95
CII
76 84 88 92 97 > :.= 80 84 89 94 100 .!!!
~ 85 85 90 96 102
90 86 91 98
96 86 93 100
100 87 95 103
Likelihood of Heat Disorders with Prolonged Exposure or strenuous Activity o Caution o Extreme Caution Danger Extreme Danger
FIGURE 11-2. NWS HEAT INDEX

HIGH WINDS
High Winds are generally short-duration events involving straight-line winds or gusts of over 50 mph, strong enough to cause property damage. High winds or a windstorm are especially dangerous in areas with significant tree stands and areas with exposed property, poorly constructed buildings, mobile homes (manufactured housing units), major infrastructure, and above-ground utility lines. A windstorm can topple trees and power lines, cause damage to residential, commercial and critical facilities, and leave tons of debris in its wake.

Damaging winds are classified as those exceeding 60 mph. Damage from such winds accounts for half of all severe weather reports in the lower 48 states and is more common than damage from tornadoes.

Wind speeds can reach up to 100 mph and can produce a damage path extending for hundreds of miles.

There are seven types of damaging winds:
• Straight-line winds - Any thunderstorm wind that is not associated with rotation; this term is used mainly to differentiate from tornado winds. Most thunderstorms produce some straight-line winds as a result of outflow generated by the thunderstorm downdraft. 222 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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• Downdrafts- A small-scale column of air that rapidly sinks toward the ground. • Downbursts - A strong downdraft with horizontal dimensions larger than 2.5 miles resulting in an outward burst or damaging winds on or near the ground. Downburst winds may begin as a microburst and spread out over a wider area, sometimes producing damage similar to a strong tornado. Although usually associated with thunderstorms, downbursts can occur with showers too weak to produce thunder.
• Microbursts - A small concentrated downburst that produces an outward burst of damaging winds at the surface. Microbursts are generally less than 2.5 miles across and short-lived, lasting only 5 to 10 minutes, with maximum wind speeds up to 168 mph. There are two kinds of microbursts: wet and dry. A wet microburst is accompanied by heavy precipitation at the surface. Dry microbursts, common in places like the high plains and the intermountain west, occur with little or no precipitation reaching the ground. • Gust front- A gust front is the leading edge of rain-cooled air that clashes with warmer thunderstorm inflow. Gust fronts are characterized by a wind shift, temperature drop, and gusty winds out ahead of a thunderstorm. Sometimes the winds push up air above them, forming a shelf cloud or detached roll cloud.
• Derecho-A derecho is a widespread thunderstorm wind caused when new thunderstorms form along the leading edge of an outflow boundary (the boundary formed by horizontal spreading of thunderstorm-cooled air). The word" derecho" is of Spanish origin and means "straight ahead." Thunderstorms feed on the boundary and continue to reproduce. Derechos typically occur in summer when complexes of thunderstorms form over plains, producing heavy rain and severe wind. The damaging winds can last a long time and cover a large area. • Bow Echo-A bow echo is a linear wind front bent outward in a bow shape. Damaging straight-line winds often occur near the center of a bow echo. Bow echoes can be 200 miles long, last for several hours, and produce extensive wind damage at the ground.

SPACE WEATHER
All weather on Earth, from the surface of the planet out into space, is influenced by the small changes the sun undergoes during its solar cycle. These variations are referred to as space weather. Sudden bursts of plasma and magnetic field structures from the sun's atmosphere-called coronal mass ejections­ together with sudden bursts of radiation, or solar flares, all cause weather effects here on Earth. Extreme space weather can cause damage to critical infrastructure, especially the electric grid. It can produce electromagnetic fields that induce extreme currents in wires, disrupting power lines, and even causing Wide-spread blackouts. In severe cases, it produces solar energetic particles, which can damage satellites used for commercial communications, global positioning, intelligence gathering, and weather forecasting.

NOAA's Space Weather Prediction Center has developed space weather scales. Descriptions of three general NOAA classifications of space weather-geomagnetic storms, solar radiation storms and radio blackouts-are included in Figure 11-3. NOAA studies have determined that different types of space weather may occur separately.

The most important impact the sun has on Earth is related to its brightness or irradiance. The sun produces energy in the form of photons of light. The variability of the sun's output is wavelength dependent:
• Most of the energy from the sun is emitted in the visible wavelengths. The output from the sun in these wavelengths is nearly constant and changes by only 0.1 percent over the course of the 11-year solar cycle.
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• At ultraviolet or UV wavelengths, solar irradiance is more variable, with changes up to 15 percent over the course of the l1-year solar cycle. This has a significant impact on the absorption of energy by ozone and in the stratosphere.
• At still shorter wavelengths, like extreme ultraviolet, solar irradiance changes by 30 to 300 percent over a period of minutes. These wavelengths are absorbed in the upper atmosphere, so they have minimal impact on the climate of Earth.
• At the other end of the light spectrum, at infrared wavelengths, solar irradiance is very stable and only changes by a percent or less over the solar cycle.

Other types of space weather can impact the atmosphere. Energetic particles penetrating into the atmosphere can change chemical constituents. These changes in minor species such as nitrous oxide (NO) can have long lasting consequences in the upper and middle atmosphere; however, it has not been determined if these have a major impact on the Earth's climate. 2241 Page Santa Clara County Operational Area Mitigation Plan 10/lS/17

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NOAA S~ncl' 'Yl'ntber Scnlt's
l'"OTE: Eacb t~' Pt of spact' wl'atbl'I' may occur sl'pal'atl'ly, Desniptions of all tbl'l'l' typtS of SpllCt wl'fttbl'l' warnings are bel'e combined into one table mel'ely to consene space, HF means higb fnquency (radio wan's), but other radio frequt'ndt's may also be affected by tbese enonts, LF means low n'('('Ju(,lIcr (radio WA"('5). F: nfers to enDt fj'tqUtDCY, Cattgo!'y Geomagnt tk StOl'ms SoiaI' RadiAtioD Stol'm'S Radio Blackouts Labt lc; (dftct & fl'('qUtDCY> (dftct & fl'tqutDCY) (dfect & fl't'qU(,DCY) M!!!Qr GI ~"fnl$ CaD C311~ ",.ak POWff grid flucnl.tions , 51 I!'\'mts result in mmor impacts OIl HF ndio in polar RI f\'Wts cau~ 'Hill.: or lUIIlor 1IlIJlO[ IDlpacls on ~t.lli l~ opellltion~, efTCC1~ on regions, F: .boul 50 tueh .,~ts per solar cycle, nth degradation of HF radio cODlDlImic.tion G1 migrAtOr)' ~lUDlaJS . Md '\1del)' ,;sibl. allfOIM ~~n of whicb can brt more thm 1 cU)' on tilt $Iuillt side of Earth. :md SI Ul 'onbern Michigan. F: aboUI 900 days per solu occuiOllml loss of radio cODtact. lJ' Rl cyc:le. DlIigalion signals used by maritime ruld
ge~ral aviation syst~ms may be
degraded for brief interl'llls, F: abollt
9S0 da,., per solar n~I. ,
Modt'tall' 01 ~"ents cau C.llse bi~,laurude pown $)'Stem~ to S3 I!'\_ts may expose peI'SOM in bigh,fl}~Dg aircraft 10 R2 t\'eDts cau~ a limited bbckolll of G2
tsperi~n(t \'oltlge a1"f1J1$, Long.dlU'llDOn .stonu$ u de\'ated odialion risk" ID UHS of high lablllde . HF odio cOlDInlmicalioM OD !be SUIllit lilly cause transfo~r d.unlge. ColTtebOU~ 10 Infrtquellt singJe,e,'eal UP~\$ of satellite operarion~ $ide of Earth. and loss of odio tonlmct S2 SMeIlilt orienlation 4Ild orbital drag predicoOD ma), art possible. POSSIble effect~ on HF propagatioD and for tens of twnUtes_ LF o.nit:atiou R2 be rtquired. HF nulio prop.gation C~ flIde II n3l'lg.non through polar regiollS. f : ~boul 25 e\'ents signals lilly also be degraded for lens of hltbt1 IltiNdes . Auroras may be ,.jslble throUghOUI I'tr solar cyd •. t3th of wbich can 13st more than J !minutes, F; abolll 300 dAys p.r soior MKhigm. F: abollt 360 d.ys per solIII' c)~lt, cUr, Crclt , ~ 03 e'~nls may Itqlllfe ,'ohage corrections at powe, S3 t\'mls can e.'tJIOSt pmous in hlp.flying lim3ft to 1R3 e"ents cause a ",ide area blackout of systems lUId mmy trigger falw .. Ianns on their • radiation rid:· in 3rt," of lugh bUI\lde _ S.ltUlIe HF odio CODlDlWllcation and loss of G3 protection de\,c.s , Satellite onen.lation problellls opentioll$ 1IlI)' expeneuce ting le. e,'enl upsets, rAdio colllact for about an bo\\r OD the S3 moy need cort«tion. Increased atmospheric drag im.1ging ~'S lem noi~. and slight solar panel 5lmlil side of Earth_ U DI',garioD R3 and component surfact charging may OCCIIT. iMfTlcitncies_ ~gnded HF rwo prop3gauon in sign.1s 1m)' be degraded for about an Inltrmit~ol U radio Da\;galion problems may polar rtgions , Na\'ig;uioo pontion errors U'e lihly F: bollt. F: .bOlu 1-10 cb)'S per sow cycle_ OCCllr, F: 130 daIS per solar c)de_ ~bo\l1 10 ~\'entsJler C\~ I ~ ( .~ch can ~:'ICted I dl\') , ~
I~ ~"ent$ 1Wl)' calIse \\1despread \'oltag~ contro I S~ ""en Is ClIO e.,<pc»e persons m higb'll)'\Dg ailcl1lft to IR~ ~\·enIS cau~ au \:iF radio probltll),$ for power S)~ttW, Nld 1I11still.:cn a radiation risk· III anlS of bigll blirude , Sattllites oDlDllmication blltckout 00 most of the G4 exclllSlon of 1:.)' usels from 3 pown gnd by some ma)' eltpeneuce memory d."ce problem s, IlWlging Slmlit side of Earth for I to 2 hours, S4 protecu,'t S}'Slems.. Satellites ma)' e:tptrience 5)'Stems noise, onell t~tian prob le.ms. and d~gn.ded 'i th HF radio CODtlIct lost <Imin8 lhis R4 surface charging . tracking and oriml:>tion problems solar panel efficiency , A blackoul of HF ndio time. LF ua\~gation signals C1Use lhat mAy nted corrtelioll. Pipelines ImY e~ence COtDmiUlIC3tioM is li1:ely through the pobr re~loM increlSed mon; in positioning for I to 2 indlKed C\lJR1IIS, HI raebo prop.s.hon sporodtc, Incre.wd nlviganon enors O\'a- 5(\'6;\1 da)~ are bOllTs, Minor dimaplions of salellitc lJ' Rebo dimlpled SQlellite-based na'~gatiOD lila)' libly , F: about 3 C\-nlU per sobr cyd. (each cm nl,~gallon are posliblc on tb~ $IUllit be degnded for bollTS, F: about 60 da)., p.r solar elected 1 dJ),), s.ide of Eanh. F: about S da}'S per solar C'yde. crcle.

EXtreOlt' G~ c"ents lIlA)' cause widespread \'ohage conlrol S5 events can expose persons in lugh-flying aircnft to LRS e'\~ts CAuse. complet. HF ndio G5 and prOteeD.\'e syslem problem! n power sys lems, a radiation risk· in IRas of high laorudc, Sattlht es bl.d:ollt on tilt entire sunlit side 0 \\1m sollie gnd s)'Slems completely blAd:.mg Ollt or IM}' be rendered usel .... . ma)' I«tl\~ ptnIWlenl ",Iu E.uth for a number of hollTS_ No HF S5 coUap~ng, md possible damage 10 tnusformm , p;on~1 cbmag~, or m~y 6penmce memor) ' prob lans , adio ooalaet with mariners and a\~. ~tors R5 Satellites may f:q>eJim~ exten D,Of slImee loss of control. luious lDIllpng d.u Do~e , and in this seclor, lJ' DI\~gatioD iigJUls cb:u'JUlg. orieutation . Irnd:ing. Iud linhge n~vigahon ploblems _ Complete HF nebo ~~perifllCt outages for many houn on problellli , Pipeline; l1lIl)' recei\'. induced cumnlf COIllllllUllC.tiODS bl.d:out5 IU'. poSSIble tbroUghOIlI the the swtlit side of Earth, causing loss tD rncluDg b\lDdreds of :unp HF ",dio nu)' be 0111 pol3r regiol1$o ~'iganoD Opel'lltiOllS \\i ll be e.'<trtmel): ~osi riorung, Satellite na\~galioD errors (or 1 to 2 <1:1)'5 in mu)' uus , LF ma), be OUI (or difficult md uror.laden . F: less than 1 t''tl\1 per <olu in po1itioning inCt~se for several hollTS bours. Salell.ilf,bll5ed M,iprion may be degraded cycle should occur, although 3/1 f\'W lIlA)' •. :~cted I on 1M sunlit side and may spread into for dAys, Bn.gbt IlIToml li~t$ 'isible at night. F' dA ' in duntion. the uight side of the Earth_ F: fnver about J dA)"5 per solar cycle , llwl I ewnl pet n~le o
,. Pl't'guant women al'(' pal'ticulal'l~' susct'ptible to l'8diation li'Sk.

FIGURE 11-3. NOAA SPACE WEATHER ScALES

HAZARD PROFILE

PAST EVENTS
Table 11-1 summarizes severe weather events in the OA since 1970, as recorded by the NOAA National Centers for Environmental Information Storm Events Database and FEMA disaster declarations, Space weather events that affected North America are also included, Santa Clara County has been included in eight FEMA declarations for severe weather events,
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TABLE 11-1. P AST SEVERE W EATHER EVENTS IMPACTING OA
FEMA I
Date of Event Event Type Declaration Location Description Number
December 19, Severe
1981 _ January storm~, flood, DR-651
8 1982 mudshdes &
, high tide
Coastal
January 21 _ s torms, .

March 30, 1983 flOOddS, shdes DR-677
an
tornadoes
Februa 12. Severe
ry storms & DR-758
March 10, 1986 flooding
Space
March 13, 1989 weather
storm
December 19, S evere 1990 - January. f
3, 1991 reeze
January 3-
February 10,
1995
February 13 -
April 19, 1995
Severe
winter
storms,
flooding,
landslides,
mud flows
Severe
winter
storms,
flooding
landslides,
mud flow
Severe
storms,
N/A
DR-894
DR-1044
DR-1046
December 28,
1996-ApriI1,
1997
flooding, mud DR-1155
and
landslides
Severe
February 2 - winter storms DR-1203
April 30, 1998 and flooding
December 15, 2002 Heavy rain
Bay Area
I
including $273 million in damage; 256 homes and 41 businesses destroyed; 6,259 Santa Clara I homes and 1,276 businesses damaged.

County
Bay Area
including Heavy rains, high winds, flooding and levee breaks caused $523 million in Santa Clara public, private, and agricultural damage.

County
Bay Area
including $407 million; 1,382 homes and 185 businesses destroyed; 12,447 homes Santa Clara and 967 businesses damaged.

County
Quebec,
Canada
A space weather storm disrupted the hydroelectric power grid in Quebec, Canada. This system-wide outage lasted for nine hours and left six million people without power.
~ai d' Area ~~Zc~~\~ a~~~I~;;:;i~~e~I::;, ;~~ ~~:u:~eV~~:~ta~~~~I~;~~~~h~~anta ~c ~ Ing CI Paula district. The freeze caused joblessness and hunger among farm Can aty ara workers. Total damage was $856 million from public buildings, utilities, and oun crop damage, 500 broken pipes affecting 5,400 homes.

Bay Area Severe winter storms, flooding, landslides and mudflows. Over 100 stations including recorded their greatest 1-day rainfall in history. Most of the storms hit Santa Clara Sacramento River Basin, which resulted in small stream flooding due to County drainage system failures. $741 million total; 11 deaths Bay Area
Including Approx. $1.1 billion total; damage to homes: major 1,322; minor 2,299; Santa Clara destroyed 267.

County
300 square miles in California were flooded including the Yosemite Valley. 48 counties Over 12,000 people were evacuated in northern California. Several levee including breaks were reported across the Sacramento and San Joaquin Valleys. Over Santa Clara 23,000 homes and business, agricultural lands, bridges, and roads were County damaged. Eight deaths resulted from this event. Overall, the state had $1.8 billion in damage.
~11 / ounties $550 million; 17 deaths from EI Nino causing widespread heavy rains, ~~n~alng Clara flooding, and landslides throughout the Bay Area. Record flooding in Santa County Clara County.

Santa Clara Two to four inches of rain fell over the OA. County 226 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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I FEMA I
Date of Event I Event Type Declaration Location I Descnption Number
Space
,-October 2003 I weather
December 1, High winds 2005
February 27, High winds 2006
July 20·25, Heat 2006
I Geomagnetic December
2006 ,storms andl-
I solar flares
December 27, High winds 2006
January 6, Frost/freeze 2007
January 4, High winds 2008
December 17, Frost/freeze 2008
February 15, High winds 2009
April 14, 2009 High winds
May 2, 2009 Dense fog
May 17, 2009 Heat
October 13, High winds 2009
December 8, Freeze
2009
January 20,
2010
10/15/17
Strong winds -
I Parts of the I This event was a series of solar flares that impacted satellite-based systems Europe and I and communications. A one-hour long power outage occurred in Sweden as 'the United a result of the solar activity. Aurorae were observed as far south as Texas States and the Mediterranean countries of Europe.

Bay area Strong winter storm brought winds gusts up to 74 mph.

Bay area . Strong winter storm brought winds gusts up to 77 mph.

Santa
Valley
Very hot weather yielded an extended period of high temperatures over 100 Clara degrees and lows in the 70s, South areas in southern Santa Clara County reached 115 degrees during the day and fell only to around 80 degrees at night. One death was reported in San Jose.

United States This event disabled Global Positioning System (GPS) signal acquisition over the United States,
Bay area A strong storm system swept across the area, knowing out power to thousands of homes and businesses.

Santa Clara Record cold wave settled upon the area with some morning lows in the 20s.

Valley Crop damage in Santa Clara County totaled approximately $50,000.

SF' A strong cyclone made landfall bringing flooding rains and high winds. The a~ ~an~'sco high winds left hundreds of thousands of residences and businesses without ~n A on erey power, property damage due to falling trees hitting cars and structures as ay reas well as damage to roads due to heavy rains throughout the areas, Bay area
Bay area
A cold low pressure system produced winter storm conditions caused several minor traffic accidents with icy conditions.

An Eastern Pacific storm produced strong wind and heavy rain causing power outages and knocking down numerous trees.

S t CI Downed trees crushed cars in San Jose and clogged major intersections. an a ara Power outages also occurred as trees brought power lines to the ground with Valley 4,600 customers losing power in San Jose.

SMantat . Cruz I Mountain fog caused a chain-reaction automobile collision. oun alns Santa
Valley
Santa
Valley
Santa
Valley
Santa
County
CI Temperatures rose into the 90s to just over 100°F in the valleys of Santa ara Clara County. Cooling centers were open across the area to mitigate heat related illnesses.

A strong low pressure system made Its way through Northern and Central Clara California accompanied by deep tropical moisture and very strong winds.

Heavy rain combined with the wind caused numerous tree, tree limbs, and electrical poles to fall throughout the area.

A storm moved across northern and central California leaving a cold air mass CI in its wake. The cold air mass led to overnight temperatures dropping below ara freezing. Black ice and unsafe speeds led to a fatality car crash, connector highway ramps from Highway 101 to Interstate 280 closed for 90 miles due to severe ice on roadway, and airport delays reported.

Strong wind brought a number of trees and limbs down across San Jose. On Clara Cherry Lane an 80·foot cedar tree toppled over, taking down a telephone pole and two tranSformers. The tree fell across the street damaging a vehicle on the other side. In Los Gatos, trees fell on Shady Lane.

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Date of Event Event Type Declaration Location Description Number
November 30, Strong winds -2011
November 30, Heavy rains 2012
I 1-May 1, 2013 High winds
October 4, Strong winds -2013
February 28, Strong winds -2014
December 10- Heavy rains
11,2014 and high -
winds
February 6,
2015
February 9,
2015
Strong winds -
Heavy rain
December 13, 2015 Strong winds -
Bay area Wind gusted up to 70 mph throughout the area downing trees and power lines.

Santa CI A series of significant winter storms impacted the district during late ara November and early December 2012. Minor urban and small stream flooding 'was observed across Sa.nla Clara County due to the heavy rainfall. County IBayarea
Bay area
Bay area
Bay area
Santa
Valley
Santa
County
Bay area
Hot weather followed by increasingly strong northeast winds lead to critical fire weather conditions.

Strong winds moved through the area that caused downed trees and poWerlines and causing several wildfires 10 ignite.

A Pacific storm system moved across the area and dropped several inches lof rainfall with gusty winds. This resulted in flooding of urban areas, small streams and creeks, and damage to power lines and trees as well as a few localized mud and rockslides.

Heavy rains and gusty winds impacted the Bay Area for several days.

Rainfall rates of 1.5 to 2 inches an hour were reported. A flash flood warning was issued for many municipalities including the Cities of Union City and Newark. Many areas around the Bay Area experienced flooding of streets, highways and creeks. In addition to the heavy rain, strong wind gusts were recorded with some reaching 83 mph. Overall rainfall totals ranged from 5.78 inches to 7.24 inches. This event led to power outages throughout the Bay ~ea: Rainfall totals in Union City \Vere 3.28 inches.

A strong winter storm brought heavy rain, gusty winds, and damage to trees CI and power lines along with some minor flooding of urban areas. Rainfall ara amounts were heaviest in the mountains with 5 to 10 inches or more occurring. Generally 1 to 3.5 inches fell in low elevation areas and urban s~ots, Tree blown down onto power!ines near Los Gatos.

Clara A stream gauge in Uvas Canyon County Park measured a 72 hour rainfall total of 8.74 inches.
! A cold front swept across the Bay Area with strong winds. Several large trees were blown down, some onto homes and automobiles.

Sources: NOAA, 2017; FEMA, 2017; ABAG, 2010
According to the USDA's Risk Management Agency, Santa Clara County received $4,958,724 in payments for insured crop losses over 2,243 affected acres as a result of heat, excess wind, frost, and cold wet weather events between 2003 and 2016 (see Table 11-2). The highest damaging year was 2015 for heat events.

LOCATION
Severe weather events have the potential to happen anywhere in the Santa Clara County OA.

Communities in low-lying areas next to streams are more susceptible to flooding. Regions near San Francisco Bay are more likely to experience fog. Wind events are most damaging to areas that are heavily wooded.
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TABLE 11-2. CROP INSURANCE CLAIMS PAID FROM HEAT, EXCESS WIND, FROST, AND COLD WET WEATH ER, 2003-2016
Crop Year Commod it Dama e Cause Acres Affected ' Indemnit Amount 2003 All Crops Heat 127 $73,315
2003 'All Crops Cold Wei Weather .86 $9,896
2004 I All Crops Heat '62 $9,093
2005 None None None None
2006 INone None None None
2007 All Crops Heat 60 $9,633
2008 All Crops Heat 190 $27,751
2008 All Crops Frost 72 $1~, ~19
2009 None None None None
2010 None None None None
2011 Cherries, Processing Apricots Cold Wet Weather, Freeze 64 '$278,610 2012 Cherries Frost 13 $11 ,000
2013 Cherries Cold Wet Weather 196 $456,697
2013 All Other Crops He~t 3 $100
2013 All Other Crops Excess Wind 22 $2,667
2014 Cherries Heal 665 $852,523
2015 Cherries, Processing Apricots, All Other Crops Heal 1,230 $3,354,322 2015 All Other Crops Frost 50 $2,805
2016 None None None None
Total 2243 $~958 , 724
Source: USDA, 2016
Atmospheric River, Heavy Rains, and Thunderstorms
The entire Santa Clara County OA is vulnerable to heavy rainfall and atmospheric river events as they make landfall in the Bay Area. These events can 'drop up to 12 inches of rain over a couple days and cause widespread flooding and disruption to road and air travel.

Thunderstorms affect relatively small localized areas, rather than large regions like winter storms and hurricane events. It is estimated that there are as many as 40,000 thunderstorms each day worldwide.

Thunderstorms can strike in all regions of the United States; however, they are most common in the central and southern states. Figure 11-4 shows the annual number of thunderstorms in the United States.

According to this figure, the OA can experience around five thunderstorms each year (NWS, 2016).

Extreme Temperatures
Extreme temperatures can occur anywhere in the OA. Extreme heat is a concern to people, animals and pets as well as local nursery crops, cut flowers, and vegetable crops . Extreme cold is usually frost and freeze damage that adversely affects local nursery crops, cut flowers, and vegetable crops.

High Winds
The entire OA is subject to high winds from thunderstorms and other severe weather events. Figure 11-5 indicates how the frequency and strength of windstorms impacts the United States and the general location of the most wind activity. The OA is located in FEMA's Wind Zone I, where wind speeds can reach up to 130 mph.
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Source: NWS,2016a
,------------------------------------------------------------------, FIGURE 11-4. ANNUAL NUMBER OF THUNDERSTORMS IN THE UNITED STATES Source: FEMA, 2010
.---~-------------------------------------------------------------, WIND ZONES IN THE UNITED STATES'"
SpotdaI WInd A ....
{;:::;:-!:-3 ·H_~ ROOiOtI
• Dw91 Wind Speod _~ WI .....
... CIOI'IIiIIItnl~ASCE 1·SIe
-:t--OUSI - 33 _._ grade
-~c
WlNDZONES
(:=JZONEI
(130 orc>h I
c::J ZONE I!
(UI()mphl

ZONE III
(2OOmphl
_ ZONEIY
(2SOmphl
Note: The black circle indicates the approximate vicinity of the OA.

FIGURE 11-5. WIND ZONES IN THE UNITED STATES
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Space Weather
A solar flare occurs when magnetic energy that has built up in the solar atmosphere is suddenly released.

The flare ejects clouds of electrons, ions, and atoms through the corona of the sun into space. These clouds typically reach earth a day or two after the event and can disrupt the power grid anywhere in the world (Global Resilience Network, 2016; NASA, 2016b).

FREQUENCY
Predicting the frequency of severe weather events in a constantly changing climate is a difficult task. The OA can expect to experience exposure to and adverse impacts from some type of severe weather event at least annually.

SEVERITY
The most common problems associated with severe storms are immobility and loss of utilities. Fatalities are uncommon, but can occur . Roads may become impassable due to flooding, downed trees, ice or snow, or a landslide. Power lines may be downed due to high winds, and services such as water or phone may not be able to operate without power.

Windstorms can be a frequent problem in the OA and have been known to cause damage to utilities. The predicted wind speed given in wind warnings issued by the National Weather Service is for a one-minute average; gusts may be 25 to 30 percent higher.

Heavy precipitation, which in the OA almost always takes the form of rain, can have Significant impacts, including crop damage, flash flooding, and JandsJides. Stormwater runoff from heavy rains can also impair water quality by washing pollutants into water bodies (EPA, 2015). Thunderstorms carry the same risks as heavy precipitation events, and depending on the type of storm, they can also serve as breeding grounds for tornados, lightning, and heavy winds, increasing risk of injury and property damage (Keller, 2008);
Extreme heat is defined as temperatures that generally remain 10 OF or more above the average high temperatures for the region for several weeks. In 2016, the highest average high temperatures occurred in July and august at 84 OF. Therefore, extreme temperatures would be considered any temperature over 95 OF for an extended time. In 2016, temperatures were recorded above 95 OF for a total of 37 days from April through October.

WARNING TIME
Meteorologists can often predict the likelihood of a severe storm or other severe weather event. This can give several days of warning time. However, meteorologists cannot predict the exact time of onset or severity of the storm. Some storms may come on more quickly and have only a few hours of warning time. The San Francisco Bay Area Weather Forecast Office of the NWS monitors weather stations and issue watches and warnings when appropriate to alert gover,runent agencies and the public of possible or impending weather events . The watches and warnings are broadcast over NOAA weather radio and are forwarded to the local media for retransmission using the Emergency Alert System.

Space weather prediction services in the United States are provided primarily by NOAA's Space Weather Prediction Center and the U.S. Air Force's Weather Agency, which work closely together to address the needs of their civilian and military user communities. The Space Weather Prediction Center draws on a variety of data sources, both space and ground-based, to provide forecasts, watches, warnings, alerts, and summaries as well as operational space weather products to civilian and commercial users. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 231

SECONDARY HAZARDS

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

Landslides occur when the soil on slopes becomes oversaturated and fails.

With fog, the secondary impacts are car crashes, with injuries and fatalities caused by traveling at high speeds with low visibility on highways and interstates, as well as air travel delays and diversions.

Possibly the most likely secondary impact of space weather on residents, businesses and visitors to OA is disruption to the electric power grid. Space weather can have an impact on advanced technologies, which has a direct impact on daily life.

EXPOSURE

POPULATION
A lack of data separating severe weather damage from flooding and landslide damage prevented a detailed analysis for exposure and vulnerability. However, it can be assumed that the entire OA is exposed to some extent to severe weather 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 black out, while populations in low-lying areas are at risk for possible flooding. Power outages can be life threatening to those dependent on electricity for life support. Isolation of these populations is a significant concern.

PROPERTY
According to the County Assessor, there are 464,223 buildings within the census tracts that define the OA. The majority of these buildings are residential. It is estimated that 20 percent of the residential structures were built without the influence of a structure building code with provisions for wind loads.

All of these buildings are considered to be exposed to the severe weather hazard, but structures in poor condition or in particularly vulnerable locations (located on hilltops or exposed open areas) may risk the most damage. The frequency and degree of damage will depend on specific locations. It is unlikely that the impacts of space weather would have a negative impact on the structures themselves.

CRITICAL FACILITIES AND INFRASTRUCTURE
All critical facilities exposed to flooding (Section 0) are also likely exposed to severe weather. Additional facilities on higher ground may also be exposed to wind damage or damage from falling trees. The most common problems associated with severe weather are loss of utilities. Downed power lines can cause blackouts, leaving large areas isolated. Phone, water and sewer systems may not function. Roads may become impassable due to fog or from secondary hazards such as landslides.

ENVIRONMENT
The environment is highly exposed to severe weather events. Natural habitats such as streams and trees are exposed to the elements during a severe storm and risk major damage and destruction. Prolonged rains can saturate soils and lead to slope failure. Flooding events caused by severe weather or snowmelt can produce river channel migration or damage riparian habitat. Storm surges can erode beachfront bluffs and redistribute sediment loads.
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VULNERABILITY

POPULATION
Vulnerable populations are the elderly, low income or linguistically isolated populations, people with life-threatening 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 severe weather events and could suffer more secondary effects of the hazard.

PROPERTY
All property is vulnerable during severe weather events, but properties in poor condition or in particularly vulnerable locations may risk the most damage. Those in higher elevations and on ridges may be more prone to wind damage. Those that are located under or near overhead lines or near large trees may be vulnerable to falling ice or may be damaged in the event of a collapse.

Loss estimations for the severe weather hazard are not based on damage functions, because no such damage functions have been generated. Instead, loss estimates were developed representing 10 percent, 30 percent and 50 percent of the replacement value of exposed structures. This allows emergency managers to select a range of potential economic impact based on an estimate of the percent of damage to the general building stock. Damage in excess of 50 percent is considered to be substantial by most building codes and typically requires total reconstruction of the structure. Table 11-3 lists the loss estimates.

TABLE 11-3. Loss POTENTIAL FOR SEVERE WEATHER
I I Estimated Loss Potential from Severe Weather JUrisdiction ~- -- ---------- --- Ex osed Value '10% Damage 30% Damage 50% Damage
Campbell $11,181,660,749 $1,118,166,075 $3,354,498,225 ~5 , 590 , 83_0,3! 4 Cupertino $13,890,786,985 $1,389,078,699 $4,167,236,096 $6,945,393,493 Gilroy $13,401,505,586 ,$1,340,150,559 : $4,020,451 ,676 $6,700,752,793 Los Altos $8,825, t87/82 $882,518,778 ,$2,647,556,335 $4,412,593,891 Los Altos Hills $3,242,710,721 $324,271,072 ' $972,813,216 $1 ,621 ,355,360 Los Gatos $10,893,322,460 $1,089,332,246 $3,267,996,738 $5,446,661,230 Milpitas $19,146,882,365 $1,914,688,237 $5,744,064,710 , $9,573,441,183 Monte Sereno $872.909,228 $87,290,923 $261,872,768 $436,454,614 Morgan Hill '$11,160,393,427 $1,116,039,343 $3,348,118,028 $5,580,196,713 Mountain View ,$25,062,452,472 $2,506,245,247 $7,518,735,742 $12,531,226,236 Palo Alto ! $_25,777,115,586 i $2,577,711,559 $7,733,134,676 $12,888,557,793 San Jose :$213,377,474,752 $21,337,747,475 $64,013,242,426 $106,688,737,376 Santa Clara (city) : $43,398,577,93.0 $4 , 339 , ~57 , 7~3 $13,019,573,379 $21,699,288,965 ~arato9a $8,143,761,638 $814,376,164 $2,44~, 128,491 $4,071,880,819 Sunnyvale ! $42,852,045,398 $4,285,204,540 $12,855,613,620 $21,426,022,699 $25,352.649,992 $2;535,264.999 $7,605,794,998 $12,676,324,996 iNJJ! :1211
Estimate of Crop Losses
According to the USDA's Risk Management Agency, the amount of claims paid for crop damage as a result of severe weather in Santa Clara County over a 14-year period was $4,958,724. According to the 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 233

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2016 California Insurance Profile from the USDA's Risk Management Agency, 54 percent of the insurable crops in California are insured with USDA Crop Insurance. To provide an adjusted estimate of losses accounting for insurable crops that are not insured, the 54 percent crop insurance coverage was factored in. According to this calculation, estimated annualized losses are $655,916 (see Table 11-4). Considering the value of crops from the 2012 Census of Agriculture as baseline crop exposure, the estimated annual losses from flood was determined to be low compared to the value of the insurable crops.

TABLE 11-4. EsTIMATED INSURABLE ANNUAL CROP Loss RESULTING FROM SEVERE WEATHER 14 Y FI diP da IAdjusted 14-year Flood Losses Estimated Annualized 2012 Value of - ear 00 nsurance al (consideri ng 54% Insured ) Losses e ro sb $4,958,724 $9,182,822 $655,916 $233,397,000
a. Crop insurance paid from USDA's Risk Management Agency for 2003-2016. b. 2012 Census of Agriculture, Santa Clara County

CRITICAL FACILITIES AND INFRASTRUCTURE
Incapacity and loss of roads are the primary transportation failures resulting from severe weather, 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, incapacitating transportation, isolating population, and disrupting ingress and egress. Of particular concern are roads providing access to isolated areas and to the elderly.

Prolonged obstruction of major routes due to landslides, debris or floodwaters can disrupt the shipment of goods and other commerce. Large, prolonged storms can have negative economic impacts for an entire region.

Severe windstorms, downed trees, and ice 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.

ENVIRONMENT
The vulnerability of the environment to severe weather is the same as the exposure.

FUTURE TRENDS IN DEVELOPMENT
All future development will be affected by severe storms, extreme temperatures, fog, high winds, and space weather. The ability to withstand impacts lies in sound land use practices and consistent enforcement of codes and regulations for new construction. The planning partners have adopted the International Building Code in response to California mandates. This code is equipped to deal with the impacts of severe weather events. Land use policies identified in general plans within the OA also address many of the secondary impacts (flood and landslide) of the severe weather hazard. With these tools, the planning partners are well equipped to deal with future growth and the associated impacts of severe weather.

SCENARIO
Although severe local storms are infrequent, impacts can be significant, particularly when secondary hazards of flood and landslide occur. A worst-case event would involve prolonged high winds during a winter storm accompanied by an atmospheric river event. Such an event would have both short-term 234 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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and longer-term effects. Initially, schools and roads would be closed due to power outages caused by high winds and downed tree obstructions. In more rural areas, some subdivisions could experience limited ingress and egress. Prolonged rain could produce flooding, overtopped culverts with ponded water on roads, and landslides on steep slopes. Flooding and landslides could further obstruct roads and bridges, further isolating residents .

ISSUES
Important issues associated with a severe weather in the OA include the following:
• Older building stock in the OA is built to low code standards or none at all. These structures could be highly vulnerable to severe weather events such as windstorms . • Cities may need to open cooling/warming stations during extreme temperature events. • Redundancy of power supply must be evaluated.
• The capacity for backup power generation is limited.
• Dead or dying trees as a result of drought conditions are more susceptible to falling during severe storm events.
• Public education on dealing with the impacts of severe weather needs to continue to be provided so that citizens can be better informed and prepared for severe weather events. In particular, fog should be considered, since fog may be downplayed despite its potential for transportation accidents.
• Debris management (downed trees, etc.) must be addressed, because debris can impact the severity of severe weather events, requires coordination efforts, and may require additional funding.
• The effects of climate change may result in an increase of heavy rain or more atmospheric storm events, and will likely lead to increased temperatures and changes in overall precipitation amounts.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 235

TSUNAMI

GENERAL BACKGROUND

TSUNAMI

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A tsunami consists of a series of high-energy waves that radiate outward like pond ripples from an area where a generating event occurs. Earthquakes may produce dis lacements of the sea floor that can set the overlying column of water in motion, initiating a tsunami, DEFINITIONS depending on the magnitude of the earthquake and the type of faulting.

Tsunamis are typically classified as local or distant. Locally generated tsunamis have minimal warning times, leaving few options except to run to high ground. They may be
accompanied by damage resulting from the triggering
earthquake due to ground shaking, surface faulting,
liquefaction or landslides.

Distant tsunamis may travel for hours before striking a coastline, giving a community a chance to implement
evacuation plans. In the open ocean, a tsunami may be only a Tsunami-A series of traveling ocean
waves of extremely long wavelength
usually caused by displacement of the
ocean floor and typically generated by
seismic or volcanic activity or by
underwater landslides.

Selche-A standing wave in an enclosed
or partially enclosed body of water such as
bays and lakes. Seiches are typically
caused when strong winds and rapid
¢lla"ge~ in atmospheric pressure or an
ElQrtl:lquake push water from one end of a
body of water to the other.
few inches or feet high, but it can travel with speeds approaching 600 miles per hour. Tsunami waves arrive at shorelines over an extended period. Figure 12-1 shows likely travel times across the Pacific Ocean for a tsunami generated along the California coastline near the San Francisco Bay Area.

As a tsunami enters the shoaling waters near a coastline, its speed diminishes, its wavelength decreases, and its height increases greatly. The first wave usually is not the largest. Several larger and more destructive waves often follow the first one. As tsunamis reach the shoreline, they may take the form of a fast-rising tide, a cresting wave, or a bore (a large, turbulent wall-like wave). The bore phenomenon resembles a step-like change in the water level that advances rapidly (from 10 to 60 miles per hour).

The configuration of the coastline, the shape of the ocean floor, and the characteristics of advancing waves play important roles in the destructiveness of the waves. Offshore canyons can focus tsunami wave energy and islands can filter the energy. The orientation of the coastline determines whether the waves strike head-on or are refracted from other parts of the coastline. A wave may be small at one point on a coast and much larger at other points. Bays, sounds, inlets, rivers, streams, offshore canyons, islands, and flood control channels may cause various effects that alter the level of damage. It has been estimated, for example, that a tsunami wave entering a flood control channel could reach a mile or more inland, especially if it enters at high tide.

The first visible indication of an approaching tsunami may be recession of water (draw down) caused by the trough preceding the advancing, large inbound wave crest. Rapid draw down can create strong currents in harbor inlets and channels that can severely damage coastal structures due to erosive scour around piers and pilings. As the water's surface drops, piers can be damaged by boats or ships straining at or breaking their mooring lines. The vessels can overturn or sink due to strong currents, collisions with other objects, or impact with the harbor bottom.
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2000km
I
FIGURE 12-1. POTENTIAL TSUNAMI TRAVEL TIMES IN THE PACIFIC OCEAN, IN HOURS Conversely, the first indication of a tsunami may be a rise in water level. The advancing tsunami may initially resemble a strong surge increasing the sea level like the rising tide, but the tsunami surge rises faster and does not stop at the shoreline. Even if the wave height appears to be small, 3 to 6 feet for example, the strength of the accompanying surge can be deadly. Waist-high surges can cause strong currents that float cars, small structures, and other debris. Boats and debris are often carried inland by the surge and left stranded when the water recedes.

At some locations, the advancing turbulent wave front will be the most destructive part of the wave. In other situations, the greatest damage will be caused by the outflow of water back to the sea between crests, sweeping all before it and undermining roads, buildings, bulkheads, and other structures. This outflow action can carry enormous amounts of highly damaging debris with it, resulting in further destruction. Ships and boats, unless moved away from shore, may be dashed against breakwaters, wharves, and other craft, or be washed ashore and left grounded after the withdrawal of the seawater. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 237 SEICHE

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A seiche is a standing wave in an enclosed or partially enclosed body of water, such as San Francisco Bay.

Seiches are typically caused when strong winds and rapid changes in atmospheric pressure or an earthquake push water from one end of a body of water to the other. The largest seiche that was ever measured in the San Francisco Bay, following the 1906 earthquake, was 4 inches high. The Bay Area has not been adversely affected by seiches (U.s. Army Corps of Engineers, 2016).

HAZARD PROFILE

PAST EVENTS
According to the National Centers for Environmental Information, the California coastline has been impacted by tsunami wave events on four dates since 2005: November 15, 2006, February 27, 2010, March 11,2011, and September 16, 2015. Together these events caused approximately $45 million in property damage. The Santa Clara County OA has never been impacted by a tsunami. The closest tsunami to affect the OA was the tsunami event on March 10, 2011 that occurred in Japan and traveled across the Pacific Ocean to create wave surges that damaged coastal areas in nearby Santa Cruz and Monterey Counties.

These counties were included in FEMA-1968-DR-CA declaration.

LOCATION
The most likely site of tsunami impacts in the Santa Clara County OA is along area creeks that would rise with floodwaters from a San Francisco Bay tsunami caused by a local earthquake. 238 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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San
FrancIsco
Bay
Figure 12·2.

Tsunami Inundation
Area
_ Tsunami Evacuation Planning
... Scenario
D Santa Clara County Boundary
(;:-J City Boundaries
Walar Bodies & Channals
lhl. tsun.mllnund.llon m>p woo prtp.rod
to ZlSsist cities and counties in fCltnltfylng
their tsunami hazard. It is intendld tor
loc,,' jurisdIctional. coastal Ivacuatlon
planning uses onty.

N
W+E
S
0 0.75 1.5 3
Miles
~TETRATECH
Map Dat~ Sources: Santa Clara County,
Cam.ns. ABAG. USDA
Figure 12-2 shows tsunami inundation mapping for areas on the southern portion of the San Francisco Bay and Coyote Creek (the northern portion of the Santa Clara County OA) prepared by the California Department of Conservation.

FREQUENCY
The frequency of tsunamis is related to the frequency of the events that cause them, so it is similar to the frequency of seismic or volcanic activities or landslides. Generally four or five tsunamis occur every year in the Pacific Basin, and those that are most damaging are generated in the Pacific waters off South America rather than in the northern Pacific.

SEVERITY
Tsunamis are a threat to life and property to anyone living near the ocean . From 1950 to 2007, 478 tsunamis were recorded globally. Fifty-one of these events caused fatalities, to a total of over 308,000 coastal residents. The overwhelming majority of these events occurred in the Pacific basin. Recent tsunamis have struck Nicaragua, Indonesia, and Japan, killing several thousand people. Property damage due to these waves was nearly $1 billion . Historically, tsunamis originating in the northern Pacific and along the west coast of South America have caused more damage on the west coast of the United States than tsunamis originating in Japan and the Southwest Pacific. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 239

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It is general consensus that the Santa Clara County OA would not likely see significant impacts from a tsunami originating in the Pacific Ocean, given the area's inland location. However, the OA would likely see minor tsunami impacts on creeks from a local earthquake event, with any floodwaters flowing up creeks impacting people visiting the creeks. A local earthquake tsunami can occur any time, and the resulting floodwater waves can carry damaging debris.

Sen
Frllnc i llGQ
B8Y
FIGURE 12-2. TSUNAMI INUNDATION AREA
240 I Page Santa Clara County Operational Area Mitigation Plan Figure 12-2.

Tsunami Inundation
Area
_ Tsunomi Evacuation Planning
- Scenario
o Sanla Clara County Boundary
City Boundaries
Waler Bodies & Channels
,..,1, U;t,inOmllnund3tlon m~p was ptlp~rtd
to assist cities a.nd counties in Id.ntttying
their tsun;)ml huard. It is Intlnded for
local Jurisdictional, coastal Ivacuatlon
pl3nnlng US'S onfy.

N
w+e
5 0 0.75 1.5 3
Miles
~TETRATECH
Map Data Sources: Santa Clara County,
comans, ABAG, USDA
10/15/17

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WARNING TIME
Typical signs of a tsunami hazard are earthquakes and/ or sudden and unexpected rise or fall in coastal water. The large waves are often preceded by coastal flooding and followed by a quick recession of the water. Tsunamis are difficult to detect in the open ocean; with waves less than 3 feet high. The tsunami's size and speed, as well as the coastal area's form and depth, affect the impact of a tsunami; wave heights of 50 feet are not uncommon. In general, scientists believe it requires an earthquake of at least a magnitude 7 to produce a tsunami.

The Pacific tsunami warning system evolved from a program initiated in 1946. It is a cooperative effort involving 26 countries along with numerous seismic stations, water level stations and information distribution centers. The National Weather Service operates two regional information distribution centers. One is located in Ewa Beach, Hawaii, and the other is in Palmer, Alaska. The Ewa Beach center also serves as an administrative hub for the Pacific warning system.

The warning system only begins to function when a Pacific basin earthquake of magnitude 6.5 or greater triggers an earthquake alarm . When this occurs, the following sequence of actions occurs:
• Data is interpolated to determine epicenter and magnitude of the event. • If the event is magnitude 7.5 or greater and located at sea, a TSUNAMI WATCH is issued. • Participating tide stations in the earthquake area are requested to monitor their gages. If unusual tide levels are noted, the tsunami watch is upgraded to a TSUNAMI WARNING. • Tsunami travel times are calculated, and the warning is transmitted to the disseminating agencies and thus relayed to the public.
• The Ewa Beach center will cancel the watch or warning if reports from the stations indicate that no tsunami was generated or that the tsunami was inconsequential.

This system is not considered to be effective for communities located close to the tsunami because the first wave would arrive before the data were processed and analyzed. In this case, strong ground shaking would provide the first warning of a potential tsunami.

SECONDARY HAZARDS
By the time a tsunami wave reaches the Santa Clara County OA, it may carry floating debris that can cause damage to any affected areas.

EXPOSURE AND VULNERABILITY

POPULATION
The population of the Santa Clara County OA is located outside of a tsunami inundation area, therefore, no population exposure exists for the tsunami hazard.

PROPERTY
No buildings are located in the tsunami inundation area in the OA, so no property exposure based on building stock exists for the tsunami hazard.

CRITICAL FACILITIES AND INFRASTRUCTURE
Critical facilities and infrastructure in the Santa Clara County OA are located outside of the tsunami inundation area, so no such exposure exists for the tsunami hazard. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 241

ENVIRONMENT

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Waterways originating from southern portion of San Francisco Bay would be exposed to the effects of a tsunami or seiche; inundation of water and introduction of foreign debris could be hazardous to the environment. All wildlife inhabiting the area is exposed. The vulnerability of aquatic habit and associated ecosystems would be highest in low-lying areas close to the southern portion of San Francisco Bay coastline.

Tsunami waves and seiches can carry destructive debris and pollutants that can have devastating impacts on all facets of the environment. Millions of dollars spent on habitat restoration and conservation in the OA could be wiped out by one significant tsunami. There are currently no tools available to measure these impacts. However, it is conceivable that the potential financial impact of a tsunami or seiche event on the environment could equal or exceed the impact on property. Community planners and emergency managers should take this into account when preparing for the tsunami hazard and considering future development.

FUTURE TRENDS IN DEVELOPMENT
Tsunami inundation areas in the OA are within flood hazard areas that are already regulated under floodplain management regulations.

SCENARIO
The worst-case scenario for the OA is a local tsunami or seiche event originating in the San Francisco Bay triggered by a seismic event. This can occur anytime and the series of floodwater waves can carry damaging debris and cause environmental impacts.

ISSUES
The Core Planning Group has identified the following issues related to the tsunami hazard for the OA:
• As tsunami warning technologies evolve, the tsunami warning capability within the OA will need to be enhanced to provide the highest degree of warning. • With the possibility of climate change, the issue of sea level rise may become an important consideration as probable tsunami inundation areas are identified through future studies. • Special attention will need to be focused on the vulnerable communities in the tsunami zone and on hazard mitigation through public education and outreach. 242 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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WILDFIRE

GENERAL BACKGROUND
A wildfire is any uncontrolled fire occurring on undeveloped land that requires fire suppression.

Wildfires can be ignited by lightning or by human activity such as smoking, campfires, equipment use, and arson.

Fire hazeuds present a considerable risk to vegetation and wildlife habitats.

Short-term Loss caused by a wildfire can includ e the destruction of timber, wildlife habitat, scenic vistas, and watersheds. Long-term effects include smaller timber harv ests, reduced access to affected recreational areas, and desb·uction of cultm ·al and economic resources and community infrastructur e. Vulnerability to flooding increases due to the destruction of watersheds. The potential for significant damage to life and property exists in areas designated as "wildland urban interface areas." where development is adjacent to densely vegetated areas.

HAZARD PROFILE

PAST EVENTS
According to the State of California Multi-Hazard Mitigation Plan and the California Department of Forestry and Fire Protection, the Santa Clara County OA experiences wildfires every two to three years. There have been two federal disaster declarations for wildfires since 1950. The following are wildfires of over 10 acres that have been recorded in or near the OA (CAL FIRE, 2016):

DEFINITIONS
Interface Area-An area
susceptible to wildfires and
where wildland vegetation
and urban or suburban
development occur
together. An example would
be smaller urban areas and
dispersed rural housing in
forested areas.

Wildfire-Fires that result
in uncontrolled destruction
of forests, brush, field crops,
gras-stands, and real and
personal property in non­
urban areas. Because of
th~jr distance from
firefig/lting resources, they
e.an be c;lfffieull to contain
and can cause a great deal
Of destruc~ion
• June 26 - July 19, 1985; "Lexington Fire" (FEMA-739-DR-CA) - This federal wildfire disaster included six counties. In Santa Clara County, the worst of the fires affected the Santa Cruz Mountains south of San Jose, threatening at least 2,000 homes and forcing the evacuation of more than 4,500 people (L.A. Times, 2016).
• October 25 - 26, 2006, Felter Fire- Burned 200 acres. • August 30 - September 2, 2007, Stevens Fire-Burned 151 acres near Stevens Canyon Reservoir.
• September 3 - 11, 2007, Lick Fire- Burned 47,760 acres at Henry Coe State Park, with four residences and 20 outbuildings destroyed.
• May 22 - 30, 2008, Summit Fire (FEMA-2766-FM-CA) - Burned 4,270 acres along with 35 residences, 64 outbuildings at Summit Road and Maymen Flats, south of the Town of Lorna Prieta.
• June 21 - 26, 2008, Whitehurst/Hummingbird Fires - Burned 794 acres at Hummingbird and 200 acres at Whitehurst.
• August 29 - 30, 2009, Pacheco Fire - Burned 1,650 acres. • September 23 - Octob er 5, 2002, "Croy Fire" (FM-2465) -13,128 acres burned. • July 21,2011, McDonald Fire- Burned 27 acres east of Morgan Hill below Anderson Lake. • July 12, 2013, Uvas Fire- Burned 50 acres along Uvas Road and Casa Lorna Road, near Calero Courtty Park and west of Morgan Hill.
• June 30 - July 1, 2014, Curie Fire - Burned 125 acres off Curie Drive south of San Jose. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 243

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• August 28 - 31, 2014, Casa Fire- Burned 80 acres along Highway 152 at Casa De Fruta. • June 30 - 3, 2015, Highway Fire - Burned 42 acres off Highway 101 near Monterey Frontage Road, south of the City of Gilroy.
• September 9 -10, 2015, Pacheco Fire- Burned 215 acres off Highway 152 at Dinosaur Point, 3 miles west of San Luis Reservoir.
• July 30 - 31, 2016, Sierra Fire - Burned 114 acres off Sierra Road and Calaveras Road. • August 17 -18,2016, Bailey Fire- Burned 100 acres off Highway 101 and Bailey Road. • September 1 - 2, 2016, Oak Fire-Burned 25 acres off Oak Glen Avenue, 2 miles west of Morgan Hill.
• September 26 - October 12,2016, Lorna Fire- Bumed 4,474 acres and destroyed 12 residences and 16 outbuildings off Lorna Prieta Road and Loma Chiquita Road, 10 miles northwest of Morgan Hill.

LOCATION
CAL FIRE's Fire and Resource Assessment Program has modeled and mapped wildfire hazard zones using a science-based and field-tested computer model that assigns a fire hazard severity zone (FHSZ) of moderate, high or very high. The FHSZ model is built from existing CAL FIRE data and hazard information based on factors such as the following:
• Fuel-Fuel may include Jiving and dead vegetation on the ground, along the surface as brush and small trees, and above the ground in tree canopies . Lighter fuels such as grasses, leaves and needles quickly expel moisture and burn rapid ly, while heavier fuels such as tree branches, logs and trunks take longer to warm and ignite. Trees killed or defoliated by forest insects and diseases are more susceptible to wildfire.
• Weather-Relevant weather conditions include temperature, relative humidity, wind speed and direction, cloud cover, precipitation amount and duration, and the stability of the atmosphere. Of particular importance for wildfire activity cne wind and thunderstorms:
.:. Strong, dry winds produce extreme fire conditions. Such winds generally reach peak velocities during the night and early morning hours .
• :. The thunderstorm season typically begins in June with wet storms, and turns dry with little or no precipitation reaching the ground as the season progresses into July and August. • Terrain-Topography includes slope and elevation. The topography of a region influences the amount and moisture of fuel; the impact of weath er conditions such as temperature and wi.nd; potential barriers to fire spread, such as highways and lakes; and elevation and slope of land forms (fire spreads more easily uphill than downhill). • Probability of Future Occurrence- The likelihood of an area burning over a 30- to 50-year time period, based on history and other factors.

The model also is based on frequency of fire weather, ignition patterns, and expected rate-of spread. It accounts for flying ember production, which is the principal driver of the wildfire hazard in densely develop.ed areas. A related concern in built-out areas is the relative density of vegetative fuels that can serve as sites for new spot fires within the urban core and spread to adjacent structures. The model refines the zones to characterize fire exposure mechanisms that cause ignitions to structures. Significant land­ use changes need to be accounted for through periodic model updates. 2441 Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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;
Figure 13-1.

Wildfire Severity Zones &
Historical Perimeters
C1 Santa Clara County Boundary
D County Boundaries
Water Bodies & Channels
Historical Fire
Perimeters
[]]J]]ll] Pre · 1955
~ 1956-1975
~ 1976-1995
~TETRATECH
16 Mop Data Sources: Sanla Cia,. County.

Miles CalTronl. CalFIRlI, USDA
Figure 13-1 shows the FHSZ mapping for the Santa Clara County OA. Table 13-1 lists the total area mapped in each zone. Most of the mapped zones are in the unincorporated county. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 245 I
Mon/e r ey
Ba y
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16 Figure 13·1.

Wildfire Severity Zones &
Historical Perimeters
D Santa Clara County Boundary
t:J County Boundaries
Water Bodies & Channels
Historical Fire
Perimeters
[[!][[] Pre - 1955
§ 1956-1975
~ 1976-1995
~ 1996-2015
Wildfire Severity Zone
Moderate
~TETRATECH
Map DIta Soure •• : Santa ClorA County.

CalTrlns. CalFIRE. USDA
FIGURE 13-1. WILDFIRE SEVERITY ZONES AND HISTORICAL PERIMETERS 246 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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TABLE 13-1. RECORD OF FIRE AFFECTING OA
Fire Hazard I I
S t Z Total Area In Wildfire Seventy Zone iArea Burned. 1878 - 2015 even y one __________________ _ FHSZ acres Acres Percent of Total
Moderate FHSZ 33,593 693 2.1
High FHSZ 372,359 35,026 9.4
Very High FHSZ 161,211 76,521 47.5
Tetal 5611163 11 40 19.8

FREQUENCY
Wildfire frequency can be assessed through review of the portion of an area burned in previous wildfire events. Table 13-1 includes a summary of CAL FIRE records of fires over the 137 years from 1878 to 2015.

About 20 percent of the mapped wildfire risk zones in the Santa Clara County OA have burned in that period.

SEVERITY
Potential losses from wildfire include human life, structures and other improvements, and natural resources. There are no recorded incidents of loss of life from wildfires in the OA. There have been multiple destructive wildfires in the OA destroying residents, thousands of acres, and evacuating people.

Given the immediate response times to reported fires, the likelihood of injuries and casualties is minimal.

Smoke and air pollution from wildfires can be a health hazard, especially for sensitive populations including children, the elderly and those with respiratory and cardiovascular diseases. Wildfire also threatens those fighting the fires. First responders are exposed to the dangers from the initial incident and after-effects from smoke inhalation and heat stroke.

WARNING TIME
Wildfires are often caused by humans, intentionally or accidentally. There is no way to predict when one might break out. Since fireworks often cause brush fires, extra diligence is warranted around the Fourth of July when the use of fireworks is highest. Dry seasons and droughts are factors that greatly increase fire likelihood. Dry lightning may trigger wildfires. Severe weather can be predicted, so special attention can be paid during weather events that may include lightning. Reliable National Weather Service lightning warnings are available on average 24 to 48 hours prior to a significant electrical storm.

If a fire does break out and spread rapidly, residents may need to evacuate within days or hours. A fire's peak burning period generally is between 1 p.m. and 6 p.m. Once a fire has started, fire alerting is reasonably rapid in most cases. The rapid spread of cellular phone and two-way radio communications in recent years has further contributed to a significant improvement in warning time.

SECONDARY HAZARDS
Wildfires can generate a range of secondary effects, which in some cases may cause more widespread and prolonged damage than the fire itself. Fires can cause direct economic losses in the reduction of harvestable timber and indirect economic losses in reduced tourism. Wildfires cause the contamination of reservoirs, destroy transmission lines and contribute to flooding. They strip slopes of vegetation, exposing them to greater amounts of runoff. This in turn can weaken soils and cause failures on slopes.

Major landslides can occur several years after a wildfire. Most wildfires burn hot and for long durations that can bake soils, especially those high in clay content , thus increasing the imperviousn ess of the ground. This increases the runoff generated by storm events, thus increasing the chance of flooding. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 247

EXPOSURE

POPULATION

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Population could not be examined by FHSZ because the boundaries of census block groups do not coincide with the zone boundaries. However, population was estimated using the residential building count in each mapped FHSZ and multiplying by the 2016 estimated average population per household.

Table 13-2 presents the results.

TABLE 13-2. POPULATION WITHIN WILDFIRE HAZARD AREAS
L Mode~Clte i.t@£ __ 1fiI9h£I::iSZ,_ __ _J\{~Iy'!:!!gbl~S_Z __ - __ _ JUriSdiction I fopLJlatlon __ , L-- ___ I I Po~~tron , __ _ Buildings Number % of Total BUlldin s Number % of Total I BUildings I Number I % of total Campbell 0 0 0.0% 0 0 0.0% 0 0 0.0%
Cupertino 0 0 0.0% 4 0.0% 8 29 0.1%
Gilroy 0 0 10.0% 3 4 0.0% 0 .0 0.0%
Los Altos 0 0 0.0% 0 0 :0.0% 0 0 0.0% ,
iO. 1% Los Altos Hills 34 100 ! 1.2% 12 6 0 0 0.0%
Los Gatos 0 0 0.0% 21 55 0.2% 2,456 7,582 24.2%
Milpitas 0 0 0.0% 0 0 0.0% 0 0 0.0%
Monte Sereno 0 0 0.0% 0 0 0.0% 410 1,171 33.7%
Morgan Hill 0 0 0.0% 0 a 0.0% 1,752 ?,630 15.2%
Mountain View 0 0 0.0% 0 0 0.0% 0 0 0.0%
Palo Alto a 0 0.0% 0 a 10.0% 1 4 0.0%
San Jose 2 9 0.0% 123 552 0.1% 109 492 0.0%
Santa Clara (city) 0 0 0.0% 0 a io.O% 0 0 0.0%
Saratoga 0 0 0.0% 4 11 0.0% 2,071 5,657 18.7%
Sunnyvale 0 0 0.0% 0 0 0 0 10.0%
Unincorporated County .13.3%
1J'otII 1.1%

PROPERTY
Property damage from wildfires can significantly alter entire communities. The number of structures in each FHSZ within the OA and their values are summarized in Table 13-3 through Table 13-5. Table 13-6 shows the general land use of parcels exposed to the wildfire hazard in unincorporated areas of the OA.

CRITICAL FACILITIES AND INFRASTRUCTURE
Table 13-7 identifies critical facilities exposed to the wildfire hazard in the OA. In the event of wildfire, there would likely be little damage to the majority of infrastructure. Most road and railroads would be without damage except in the worst scenarios. Power lines are the most at risk to wildfire because most are made of wood and susceptible to burning. In the event of a wildfire, pipelines could provide a source of fuel and lead to a catastrophic explosion.
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TABLE 13-3. EXPOSURE AND V ALUE OF STRUCTURES IN VERY HIGH WILDFIRE HAZARD AR EAS JUrisdiction BUildings \,'C!lue E~~o~d _ _ _ ________ J % of Total Ex osed Structure Contents Total Re lacement Value
Campbell 0 1$0 $0 $0 0.0%
Cuperilno 8 $4 , 430 , n~ $2, 21~, 367 $6,646,102 0.0%
Gilroy 0 1$0 $0 $0 0.0%
Los Altos 0 $0 $0 $0 0.0% ,
Los Altos Hills 0 1$0 $0 $0 0.0%
Los Gatos 2,4~~ , $2,020,032,294 1$1,481,843,045 $3,501,875,339 32.1% Milpitas 0 1$0 '$0 $0 0.0%
Monte Sereno 410 $214,752,042 $107,376,021 $322,128,063 36.9% Morgan Hill 1,752 1$718,520,327 $374,497,669 $1 ,093,017,996 9.8% Mountain View 0 $0 $0 $0 0.0%
Palo Alto $103,393 $51.697 $155.090 0.0%
San Jose 109 $48,455,379 $32.806,811 $81,262,190 0.0%
Santa Clara (city) 0 $0 $0 $0 0.0%
Saratoga 2.071 $1 ,352,630,982 . $863,254 ,769 $2,215,885,752 27.2% 0 $0 $0 $0
$3,050,159,884 $5,370,794,371
TABLE 13-4. EXPOSURE AND VALUE OF STRUCTURES IN HIGH WILDFIRE HAZARD AREAS BUildings V~IIlP Evnosed 1% of Total JUrisdiction ----=-:...=r - -----.------.

Ex osed Structure Contents Total Re laceme nt Value
Campbell 0 $0 $0 $0 0.0%
Cupertino 1 $299,414 $149.707 $449,120 0.0%
Gilroy 3 $5,388,313 $5,211,943 $10,600,256 0.1%
Los Altos 0 $0 $0 $0 0.0%
Los Altos Hills 2 $1,712,545 $856,272 $2,568,817 0.1%
Los Gatos 21 $17,090,786 $11 ,984,620 ' $29,075,407 0.3% Milpitas 0 $0 $0 $0 0.0%
Monte Sereno 0 $0 $0 $0 0.0% ,
Morgan Hill 0 $0 $0 $0 0.0%
Mountain View 0 $0 $0 $0 0.0%
Palo Alto 0 $0 $0 $0 0.0%
San Jose 123 ,$101,534,540 $75,587,110 $177-,121,649 0.1% Santa Clara (city) 0 $0 $0 1$0 0.0%
Saratoga 4 $1,395.833 $697,916 $2.093,749 0.0%
Sunnyvale 0 $0 $0 $0 0.0%
Unincorporated County 2,445 $2,762,305,929 $2,293,960,965 $5,056,266,893 19.9% Tot I $5 218 175.892
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TABLE 13-5. EXPOSURE AND VALUE OF STRUCTURES IN MODERATE WILDFIRE HAZARD AREAS I BUildings Value Exposed % of Total JUrisdiction - - .- -.- - -- - .

Ex o sed Structure Contents ,Total Re lacement Value
Campbell 0 $0 $0 $0 0.0%
Cupertino 0 $0 $0 $0 0.0%
Gilroy 0 $0 1$0 $0 0.0%
Los Altos 0 $0 $0 $0 0.0% '
Los Altos Hills 34 $20.249.594 1$10.124.797 $30,374,391 0.9% Los Gatos 0 $0 $0 $0 0,0%
Milpitas 0 1$0 , $0 $0 0,0%
Monte Sereno 0 1$0 $0 $0 0.0%
Morgan Hill 0 1$0 $0 $0 0.0%
Mountain View 0 $0 $0 $0 0.0%
Palo Alto 0 $0 $0 $0 0.0%
San Jose 2 $607,153 $303,576 $910,729 0.0%
Santa Clara (city) 0 $0 $0 $0 0,0%
Saratoga 0 $0 $0 $0 0.0%
Sunnyvale 0 $0 $0 $0 0.0%
Unincorporated County 959 $610,543,345 $433, 143j 162 $1,043,686,507 4.1% t otal 995 $831400091 $443,571 ~35 $1074,971,627 0.2%
TABLE 13-6. LAND USE WITHIN THE WILDFIRE HAZARD AREAS
T pe of Land Use ! Mod~r9t~Se~~ritl Zone_ J Hig ~ ?_everlty ~ l ~l)'Jjlg h S~~~ri ty_Zon~ y Area acre s % of total Area acres) i % of total Area (acre s % of total Agricultural 32,38.4 9.73 2,144.1 0,58 576,3 ,0.39
General/Institutional 0.0 0.00 202.1 0.05 19.9 0.01
Open Space 28,491.3 85.58 365,560.4 98.73 145,633.9 98.17 Low Density Residential 1,561.4 4.69 2,366.4 0.64 2,122.6 1.43 High Density Residenti/il 0,0 0.00 0,0 0.00 0.0 0,00
Commercial 0,0 0.00 0,0 0,00 0,0 0,00
Industrial 0,0 0.00 0,00 0,0 0,00
Total 3-3291.2 100% 10G% 1_
TABLE 13-7. CRITICAL FACILITIES AND INFRASTRUCTURE IN WILDFIRE HAZARD AREAS I Number of Critical FaCilities In Hazard Zone Type of Critical Facility - - - -- ., - - - _ .. , ---- - -- Moderate Hi h Ve Hi h
Emergency Resp~nse I PU.blic Health §. Safety 2 6 6
Infrastructure Lifeline 31 74 55
Military Facilities 0 ,a 0
Recovery Facilities 0 0 0
Socioeconomic Facilities '1 5 11
Hazardous Materials 0 2 a
Total 3' 87 12
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There are registered hazardous material containment sites in wildfire risk zones in the OA. During a wildfire, containers for these materials could rupture due to excessive heat and act as fuel for the fire, causing rapid spreading and escalating the fire to unmanageable levels. In addition they could leak into surrounding areas, saturating soils and seeping into surface waters, and have a disastrous effect on the environment.

ENVIRONMENT
Fire is a natural and critical ecosystem process in most terrestrial ecosystems, dictating in part the types, structure, and spatial extent of native vegetation. However, wildfires can cause severe environmental impacts:
• Damaged Fisheries-Critical fisheries can suffer from increased water temperatures, sedimentation, and changes in water quality.
• Soil Erosion - The protective covering provided by foliage and dead organic matter is removed, leaving the soil fully exposed to wind and water erosion. Accelerated soil erosion occurs, causing landslides and threatening aquatic habitats. • Spread of Invasive Plant Species - Non-native woody plant species frequently invade burned areas. When weeds become established, they can dominate the plant cover over broad landscapes, and become difficult and costly to control. • Disease and Insect Infestations - Unless diseased or insect-infested trees are swiftly removed, infestations and disease can spread to healthy forests and private lands. Timely active management actions are needed to remove diseased or infested trees. • Destroyed Endangered Species Habitat-Catastrophic fires can have devastating consequences for endangered species.
• Soil Sterilization- Topsoil exposed to extreme heat can become water repellant, and soil nutrients may be lost. It can take decades or even centuries for ecosystems to recover from a fire. Some fires burn so hot that they can sterilize the soil.

Many ecosystems are adapted to historical patterns of fire occurrence. These patterns, called "fire regimes," include temporal attributes (e.g., frequency and seasonality), spatial attributes (e.g., size and spatial complexity), arid magnitude attributes (e.g., intensity and severity), each of which have ranges of natural variability. Ecosystem stability is threatened when any of the attributes for a given fire regime diverge from its range of natural variability.

VULNERABILITY
Structures, above-ground infrastructure, critical facilities and natural environments are all vulnerable to the wildfire hazard. There is currently no validated damage function available to support wildfire mitigation planning. Except as discussed in this section, vulnerable populations, property, infrastructure and environment are assumed to be the same as described in the section on exposure.

POPULATION
There are no recorded incidents of loss of life from wildfires within the OA. Given the immediate response times to reported fires, the likelihood of injuries and casualties is minimal; therefore, injuries and casualties were not estimated for the wildfire hazard.

Smoke and air pollution from wildfires can be a severe health hazard, especially for sensitive populations, including children, the elderly and those with respiratory and cardiovascular diseases. Smoke generated by wildfire consists of visible and invisible emissions that contain particulate matter (soot, tar, water 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 251

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vapor, and minerals), gases (carbon monoxide, carbon dioxide, nitrogen oxides), and toxics (formaldehyde, benzene). Emissions from wildfires depend on the type of fuel, the moisture content of the fuel, the efficiency (or temperature) of combustion, and the weather. Public health impacts associated with wildfire include difficulty in breathing, odor, and reduction in visibility.

Wildfire may also threaten the health and safety of those fighting the fires. First responders are exposed to the dangers from the initial incident and after-effects from smoke inhalation and heat stroke.

PROPERTY
Loss estimations for the wildfire hazard are not based on damage functions, because no such damage functions have been generated. Instead, loss estimates were developed representing 10 percent, 30 percent and 50 percent of the replacement value of exposed structures. This allows emergency managers to select a range of economic impact based on an estimate of the percent of damage to the general building stock. Damage in excess of 50 percent is considered to be substantial by most building codes and typically requires total reconstruction of the structure. Table 13-8 lists the loss estimates for the general building stock for jurisdictions that have an exposure to a fire hazard severity zone (the aggregate of the 3 zones assessed).

Campbell $0 $0 1$0 1$0
Cupertino $7,095,222 $709,522 $2,128,567 !$3,547;611
Gilroy $10,600,256 $1,060,026 1$3,180,077 $5,300,128
Los Altos $0 $0 '$0 ,SO
Los Altos Hills $32,943,208 1$3,294,321 ; $9,882,962
j - - -
1$16,471,604
Los Gatos $3,530,950,746 $353,095,075 $1,059,285,224 $1 ,765,475,373 Milpitas $0 $0 1$0 $0
Monte Sereno $322,128,063 $32,212,806 $96,638,419 . $161,064,031 Morgan Hili $1,093,017,996 $109,301,800 : $327,905,399 1 $546,508,998 Mountain View $0 $0 ' $0 '$0
Palo Alto $155,090 $15,509 $46,527 :$77,545
San Jose $259,294,568 $25,929,457 $77,788,370 . $129,647,284 Santa Clara (city) $0 $0 $0 ,$0
Saratoga $2,217,979,501 $221,797,950 $665,393,850 ' $1 ,108,989,750 Sunnyvale $0 $0 $0 ·$0
Unincorporated County $11,470,747,772 $1,147,074,777 $3,441,224,331 $5,735,373,886 Total 518.944 912JI20 ,118941491 ;242 $5.883.473,726 $9,472,456.210

CRITICAL FACILITIES AND INFRASTRUCTURE
Critical facilities of wood frame construction are especially vulnerable during wildfire events. In the event of wildfire, there would likely be little damage to most infrastructure. Most roads and railroads would be without damage except in the worst scenarios. Power lines are the most at risk from wildfire because most poles are made of wood and susceptible to burning. Fires can create conditions that block or prevent access and can isolate residents and emergency service providers. Wildfire typically does not have a major direct impact on bridges, but it can create conditions in which bridges are obstructed. Many 252 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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bridges in areas of high to moderate fire risk are important because they provide the only ingress and egress to large areas and in some cases to isolated neighborhoods.

FUTURE TRENDS IN DEVELOPMENT
Santa Clara County has been one of the state's fastest growing counties over the past 10 years, avej·aging a 1.21-percent increase in population per year from 2005 through 2015. The highly urbanized portions of the OA have little or no wildfire risk exposure. However, ongoing development can create the potential for the expansion of urbanized areas into wildland areas. The expansion of the wildland urban interface can be managed with strong land use and building codes. The OA is well equipped with these tools and this planning process has assessed capabilities with regards to the tools. As the OA experiences future growth, it is anticipated that the exposure to this hazard will remain as assessed or even decrease over time due to these capabilities.

SCENARIO
A major wildfire in the OA might begin with a water shortage causing tinder-like wildlands and "Red Flag" conditions occurring, indicating a combination of higher than normal temperatures, low humidity and winds blowing from the east across California to the ocean. Lightning strikes or human carelessness with combustible materials could trigger a multitude of small isolated fires.

The embers from these smaller fires could be carried miles by hot, dry winds. Fires that start in flat areas move slower, but wind still pushes them. It is not unusual for a wildfire pushed by wind to burn the ground fuel and later climb into the crown and reverse its track. This is one of many ways that fires can escape containment, typically during periods when. response capabilities are overwhelmed. These new small fires would most likely merge. Suppression resources would be redirected from protecting the natural resources to saving more remote subdivisions.

The worst-case scenario would include an active fire season throughout the American west, spreading resources thin. Firefighting teams would be exhausted or unavailable. Many federal assets would be responding to other fires that started earlier in the season.

To further complicate the problem, heavy rains could follow, causing flooding and landslides and releasing tons of sediment into rivers, permanently changin.g floodplains and damaging sensitive habitat and rrparian areas. Such a fire followed by rain could release millions of cubic yards of sediment into streams for years, creating new floodplains and changing existing ones. With the vegetation removed from the watershed, stream flows could easily double. Floods that could be expected every 50 years may occur every couple of years. With the streambeds unable to carry the increased discharge because of increased sediment, the floodplains and floodplain elevations would increase.

ISSUES
The major issues for wildfire are the following:
• Public education and outreach to people living in or near the fire hazard zones should include information about and assistance with mitigation activities such as defensible space, and advance identification of evacuation routes and safe zones. • The OA has been under multi-year drought conditions and mandatory water rations. • Wildfires could cause landslides as a secondary natural hazard. • Climate change could affect the wildfire hazard.
• Future growth into interface areas should continue to be managed. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 253

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• Area fire districts need to continue to train on wildland-urban interface events. • Vegetation management activities. This would include enhancement through expansion of the target areas as well as additional resources.
• Regional consistency of higher building code standards such as residential sprinkler requirements and prohibitive combustible roof standards. • Fire department water supply in high risk wildfire areas. • Expand certifications and qualifications for fire department personnel. Ensure that all firefighters are trained in basic wildfire behavior, basic fire weather, and that all compan y officers and chief level officers are trained in the wildland command and strike team leader level.
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CLIMATE CHANGE

GENERAL BACKGROUND
WHAT IS CLIMATE CHANGE?
Climate, consisting of patterns of temperature, precipitation, humidity, wind and seasons, plays a fundamental role in shaping natural ecosystems and the human economies and cultures that depend on them. "Climate change" refers to changes over a long period of time. Worldwide, average temperatures have increased 1.78°F since 1880 (NASA, 2017). Although this change may seem small, it can lead to large changes in climate and weather.

The warming trend and its related impa cts are caused by increasing concentrations of carbon dioxide and other greenhouse gases in the earth's atmosphere. Greenhouse gases are gases that trap heat in the atmosphere, resulting in a warming effect. Carbon dioxide is the most commonly known greenhouse gas; however, methane, nitrous oxide and fluorinated gases also contribute to warming. Emissions of these gases come fro m a variety of sources, such as the combustion of fossil fuels, agricultural production, changes in land use and volcanic eruptions. Accorcling to the U.S. Environmental Protection Agency (EPA), carbon dioxide concentrations measured about 280 parts per million before the industrial era began in the late 1700s and reached 401 parts per million in 2015 (EPA, 2016) (see Figure 14-1). In addition, the concentration of methane has almost doubled and nitrous oxide is being measured at a record high of 328 parts per billion (EPA, 2016a). In the United States, electricity generation is the largest source of these emission, followed by transportation (EPA, 2016b).

Scientists are able to place this rise in carbon dioxide in a longer historical context through the measurement of carbon dioxide in ice cores. According to these records, carbon dioxide concentrations in the atmosphere are the highest that they have been in 650,000 years (NASA, 2016). According to NASA, most of this trend is very likely human-induced and it is proceeding at an unpr cedented rate (NASA, 2016). There is broad scientific consensus (97 percent of scientists) that climate-warming trends are very likely due to human activities (NASA, 2016). Unless emissions of greenhouse gases are substantially reduced, this warming trend is expected to continue.

Climate change will affect the people, property, economy and ecosystems of the Santa Clara County OA in a variety of ways. Climate change impacts are most frequently associated with negative consequences, such as increased flood vulnerability or increas ed heat-related illnesses/ public health concerns; however, other changes may present opportunities. The most important effect for the development of this plan is that climate change will have a measurable impact on the occurrence and severity of natural hazards.

How CLIMATE CHANGE AFFECTS HAZARD MITIGATION
An essential aspect of hazard mitigation is predicting the likelihood of hazard events. Typically, predictions are based on statistical projections from records of past events. This approach assumes that the likelihood of hazard events remains essentially unchanged over time. Thus, averages based on the past frequencies of, for example, floods are used to E!stimate future frequencies: if a river has flooded an average of once every 5 years for the past 100 years, then it can be expected to continue to flood an average of once every 5 years.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 255 E 450
a. .e- 400
c o 350 .. .., .. ..

C
~ c
8 GI
."
')c
,2
."
c o .D ..
300
250
200
150
100
so
d 0
800,000 BCE to 2015 CE
-800,000 -600,000 -400,000 -200,000
Year (negative values = BCE)

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Source: EPA, 2016
1950 to 2015 CE
o 1950 1960 1970 1980 1990 2000 2010 2020
Year
FIGURE 14-1. GLOBAL CARBON DIOXIDE CONCENTRATIONS OVER TIME For hazards that are affected by climate conditions, the assumption that future behavior will be equivalent to past behavior is not valid if climate conditions are changing. As flooding is generally associated with precipitation frequency and quantity, for example, the frequency of flooding will not remain constant if broad precipitation patterns change over time. Specifically, as hydrology changes, storms currently considered to be a l-percent-annual-chance event (I DO-year flood) might strike more often, leaving many communities at greater risk. The risks of lan,dslide, severe storms, extreme heat and wildfire are all affected by climate patterns as well. For this reason, an understanding of climate change is pertinent to efforts to mitigate natural hazards. Information about how climate patterns are changing provides insight on the reliability of future hazard projections used in mitigation analysis. This chapter summarizes current understandings about climate change in order to provide a context for the recommendation and implementation of hazard mitigation measures.

CURRENT INDICATORS OF CLIMATE CHANGE
The major scientific agencies of the United States and the world - including NASA, NOAA and the Intergovernmental Panel on Climate Change (IPCC) - agree that climate change is occurring. Multiple temperature records from all over the world have shown a warming trend. The IPCC has stated that the warming of the climate system is unequivocal (IPCC, 2014). Sixteen of the 17 warmest years on record occurred since 2001, and 2015 was the warm est year on record (NASA; 2017).

Rising global temperatures have been accompanied by other changes in weather and climate. Many places have experienced changes in rainfall resulting in more intense rain, as well as more frequ ent and severe heat waves (IPCe, 2014). The planet's oceans and glaciers have also experienced changes: oceans are warming and becoming more acidic, ice caps are melting, and sea levels are rising (NASA, 2016). 256 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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Global sea level has risen approximately 6.7 inches, on average, in the last 100 years (NASA, 2016). This has already put some coastal homes, beaches, roads, bridges, and wildlife at risk (USGCRP, 2009). At the time of the development of this plan, NASA reports the following trends (NASA, 2016):
• Carbon Dioxide - Increasing trend, currently at 405.6 parts per million. • Global Temperature - Increasing trend, increase of 1.7°F since 1880. • Arctic Ice Minimum - Decreasing trend, 13.3 percent per decade. • Land Ice - Decreasing trend, 281.0 gigatonnes per year. • Sea Level-Increasing trend, 3.4 millimeters (0.04 inches) per year.

PROJECTED FUTURE IMPACTS
The Third National Climate Assessment Report for the United States indicates that impacts resulting from climate change will continue through the 21st century and beyond. Although not all changes are understood at this time and the impacts of those changes will depend on global emissions of greenhouse gases and sensitivity in human and natural systems, the following impacts are expected in the United States (NASA, 2016):
• Temperatures will continue to rise.
• Growing seasons will lengthen.
• Precipitation patterns will change.
• Droughts and heat waves will increase.
• Hurricanes will become stronger and more intense.
• Sea level will rise 1-4 feet by 2100.
• The Arctic may become ice free.

The California Climate Adaptation Planning Guide outlines the following climate change impact concerns for the Bay Area Region communities (Cal EMA et al., 2012):
• Increased temperature.
• Reduced precipitation.
• Sea level rise - coastal inundation and erosion.
• Public health - heat and air pollution.
• Reduced agricultural productivity.
• Inland flooding.
• Reduced tourism.

Some of these changes are direct or primary climatic changes, such as increased temperature, while others are indirect climatic changes or secondary impacts resulting from these direct changes, such as heat and air pollution. Some direct changes may interact with one another to create unique secondary impacts. These primary and secondary impacts may then result in impacts on human and natural systems. The primary and secondary impacts likely to effect the OA are summarized in Table 14-1.

Climate change projections contain inherent uncertainty, largely derived from the fact that tl1ey depend on future greenhouse gas emission scenarios. Generally, the uncertainty in greenhouse gas emissions is addressed by the presentation of differing scenarios: low-emissions or high-emissions scenarios. In Jow­ emissions scenarios, greenhouse gas emissions are reduced substantially from current levels. In high­ emissions scenarios, greenhouse gas emissions generally increase or continue at current levels.

Uncertainty in outcomes is generally addressed by averaging a variety of model outcomes. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 257

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TABLE 14-1. SUMM ARY OF PRIM ARY AND SECOND ARY IMPACTS LIKELY TO AFFECT THE OA Pnmar 1m act Secondar 1m act Exam Ie Human and Natural S stem 1m acts • Increased frequency of illness and death
Increased temperature Heat wave • Increased stress on mechanical systems, such as HVAC systems
Increased temperature and
changes in precipitation Changed seasonal patterns
• Reduced agricultural productivity
Increased
andlor
precipitation
Sea level rise
temperature Drought
reduced
Reduced Snowpack
• Reduced tourism
• Reduced agricultural productivity
• Decreased water sUI>Ply
'. Decreased water supply
• Reduced tourism
• Loss of assets and tax base Permanent inundation of previously dry land • Loss of coastal habitat Larger area impacted by extreme high tide • More people and structures impacted by storms Increased coastal erosion • Loss of assets and tax base • Decreased water supply Saltwater intrusion into freshwater systems • Ecosystem disruption Increased extreme events, including severe • More frequent disruption to systems resulting from severe Changes in wind patterns storms and ,fires storms
Ocean acidification • Decreased biodiversity in marine ecosystems Adapted and expanded from California Adaptation Planning Guide: Planning for Adaptive Communities Despite this uncertainty, climate change projections present valuable information to help guide decision­ making for possible future conditions . The following sections summar ize information dev eloped for the Santa Clara County OA by Cal-Adapt , a reso urce for public information on how climate change might impact local communities, based on the most current data availab le.

Temperature
The historical (1961-1990) average temperature in Santa Clara County is 60.2°F. By 2090, the average temperature is expected to increase above this baseline by 3.4°F and 5.8°F in the low- and high-emissions scenarios, respec tively (see Figure 14-2).

Extreme Heat
The extreme heat day temperature threshold for the OA is 91°F. The historical average number of extreme heat days is four. The number of extreme heat days, the number of warm nights (62°F threshold), the number of heat waves and the duration of heat waves are all expected to increase over the next century (see Figure 14-3).

Precipitation
Preci pitation projections for Caljfornia remain uncertain. Models show differin g impac ts from slightly wetter winters to slightly dJ'ier win ters, with the potential for a 10- to 20-percent decrease in total annual precipit ation. Changes in precipita tion patterns, coupled with warmer temperatures, may lead to significant changes in hydrology. In high-emissions scenarios , more precipitation may fall as rain rather than snow and this snow may melt earlier in the season, thus impacting the timing of changes in stream flow and flooding (Cal-Adapt, 2016).
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Snow Pack
While there are no snow water equivalency measurements for the OA, Cal-Adapt indicates that parts of California should expect snow pack levels to be reduced by up to 25 inches from the baseline (1961-1990) by 2090.

GeI. OF
G4.0F
GJ. OF
::II!i., OF
l"3I!iO l"3Sa , ~Qa ,~2i) ;xJII!IQ ;xJ~O
-- Low Emissions Scenario
High Emissions Scenari-o
Historic M,easuremen"t::s
,~SO
FIGURE 14-2. OBSERVED AND PROJECTED AVERAGE TEMPERATURES IN SANTA CLARA COUNTY 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 259

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COUNTY OF SANTA CLARA & SANTA CLARA COUNTY FIRE
100
90 80
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0 70
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:J: 60 Q.I
E
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S 50
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0 ~ 40
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10 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 Annual timestep from 1950 to 2099
Hislorical Avg . # Extreme Heat Days: 4 8 Exlreme Heal Dey Threshold: 91°F FIGURE 14-3. PROJECTED NUMBER OF EXTREME HEAT DAYS BY YEAR FOR OA Wildfire
All vafues based on
Wildfire risk is expected to change in the coming decades (see Figure 14-4). Under both high- and low­ emissions scenarios, the change in area burned in Santa Clara County may slightly increase or remain about the same until 2050 and then decrease by 10 to 20 percent by 2085. 260 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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J.D
~2 0
Low Emissions 5ce·nario ~ BI )
High Emissions Scenari 0 ~A2 J
FIGURE 14-4. PROJECTED C HANGES IN FIRE RISK IN SANTA CLARA COUNTY, RELATIVE TO 2010 LEVELS

RESPONSES TO CLIMATE CHANGE
Communities and governments worldwide are working to address, evaluate and prepare for climate changes that are likely to impact communities in coming decades. Generally, climate change discussions encompass two separate but inter-related considerations: mitigation and adaptation . The term "mitigation" can be confusing, because its meaning changes across disciplines:
• Mitigation in restoration ecology and related fields generally refers to policies, programs or actions that are intended to reduce or to offset the negative impacts of human activities on natural systems. Generally, mitigation can be understood as avoiding, minimizing, rectifying, reducing or eliminating, or compensating for known impacts (CEQ, 1978). • Mitigation in climate change discussions is defined as "a human intervention to reduce the impact on the climate system." It includes strategies to reduce greenhouse gas sources and emissions and enhance greenhouse gas sinks (EPA, 2013). • Mitigation in emergency management is typically defined as the effort to reduce loss of life and property by lessening the impact of disasters (FEMA, 2013).

In this chapter, mitigation is used as defined by the climate change community. In the other chapters of this plan, mitigation is primarily used in an emergency management context.

The IPCC defines adaptation as "the process of adjustment to actual or expected climate and its effects." Mitigation and adaptation are related, as the world's ability to reduce greenhouse gas emissions will affect the degree of adaptation that will be necessary. Moreover, some initiatives and actions can both reduce greenhouse gas emissions and support adaptation to likely future conditions. The ability to adapt to changing conditions is often referred to as adaptive capacity, which is "the ability of systems, 10/15/17 5anta Clara County Operational Area Mitigation Plan Page I 261

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institutions, humans and other organisms to adjust to potential damage, to take advantage of opportunities, or to respond to consequences" (IPCC, 2014).

Societies across the world are facing the need to adapt to changing conditions and to identify ways to increase their adaptive capacity. Some efforts are already underway. Farmers are altering crops and agricultural methods to deal with changing rainfall and rising temperature; architects and engineers are redesigning buildings; planners are looking at managing water supplies to deal with droughts or flooding.

Adaptive capacity goes beyond human systems, as some ecosystems show a remarkable ability to adapt to change and to buffer surrounding areas from the impacts of change. Forests can bind soils and hold large volumes of water during times of plenty, releasing it through the year; floodplains can absorb vast volumes of water during peak flows; coastal ecosystems can hold out against storms, attenuating waves and reducing erosion. Other ecosystem services-such as food provision, timber, materials, medicines and recreation-can provide a buffer to societies in the face of changing conditions. Ecosystem-based adaptation is the use of biodiversity and ecosystem services as part of an overall strategy to help people adapt to the adverse effects of climate change. This includes the sustainable management, conservation and restoration of specific ecosystems that provide key services.

Assessment of the current efforts and adaptive capacity of the planning partners participating in this hazard mitigation plan are included in the jurisdiction-specific annexes in Volume 2.

VULNERABILITY ASSESSMENT- HAZARDS OF CONCERN
The following sections provide information on how each identified hazard of concern for this planning process may be impacted by climate change and how these impacts may alter current exposure and vulnerability to these hazards for the people, property, critical facilities and the environment in the OA.

DAM AND LEVEE FAILURE
Climate Change Impacts on the Hazard
On average, changes in California's annual precipitation levels are not expected to be dramatic; however, small changes may have significant impacts for water resource systems, induding dams and levees.

Dams and levees are designed partly based on assumptions about a river's flow behavior, expressed as hydrographs. Changes in weather patterns can have significant effects on the hydrograph used for the design of a dam or levee. If the hygrograph changes, it is conceivable that the dam or levee can lose some or all of its designed margin of safety, also known as freeboard.

In the case of dams, if freeboard is reduced, dam operators may be forced to release increased volumes earlier in a storm cycle in order to maintain the required margins of safety. Such early releases of increased volumes can increase flood potential downstream. According to the California Department of Water Resources, flood flows on many California rivers have been record-setting since the 1950s. This means that water infrastructure, such as dams, have been forced to manage flows for which they were not designed (DWR, 2007). The California Division of Dam Safety has indicated that climate change may result in the need for increased safety precautions to address higher winter runoff, frequent fluctuations of water levels, and increased potential for sedimentation and debris accumulation from changing erosion patterns and increases in wildfires. According to the Division, climate change also wiII impact the ability of dam operators to estimate extreme flood events (DWR, 2008). 262 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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Dams are constructed with safety features known as "spillways." Spillways are put in place on dams as a safety measure in the event of the reservoir filling too quickly. Spillway overflow events, often referred to as "design failures," result in increased discharges downstream and increased flooding potential.

Although climate change will not increase the probability of catastrophic dam failure, it may increase the probability of design failures.

In the case of levees, a reduction in freeboard caused by a changing hydro graph means that a levee may no longer protect an area against the design-storm standard for which it was originally built (for example I-percent-annual chance). This means that risk to the area that a levee is protecting from inundation will increase. Levee accreditation may be rescinded, resulting in currently protected areas being mapped within a flood hazard area.

Exposure, Sensitivity and Vulnerability

POPULATION
Population exposure and vulnerability to the dam and levee failure hazard are unlikely to change as a result of climate change.

PROPERTY
Property exposure and vulnerability to the dam failure hazard are unlikely to change as a result of climate change. However, if areas previously protected by accredited levees are mapped in a special flood hazard area, the assets considered to be exposed to the flood hazard may increase.

CRITICAL FACILITIES
The exposure and vulnerability of critical facilities are unlikely to change as result of climate change.

Dam owners and operators are sensitive to the risk and may need to alter maintenance and operations to account for changes in the hydro graph and increased sedimentation. Critical facility owners and operators in levee failure inundation areas should always be aware of residual risk from flood events that may overtop the levee system.

ENVIRONMENT
The exposure and vulnerability of the environment to dam and levee failure are unlikely to change as a result of climate change . Ecosystem services may be used to mitigate some factors that could increase the risk of design failures, such as increasing the natural water storage capacity in watersheds above dams.

ECONOMY
Changes in the dam failure hazard related to climate change are unlikely to affect the local economy.

Economic impacts may result from changes to the levee failure hazard if accreditation is lost.

DROUGHT
Climate Change Impacts on the Hazard
The long-term effects of climate change on regional water resources are unknown, but global water resources are already experiencing the follOWing stresses without climate change :
• Growing populations.
• Increased competition for available water.
• Poor water quality.
• Environmental claims.
• Uncertain reserved water rights.
• Groundwater overdraft.
• Aging urban water infrastructure.
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With a warmer climate, droughts could become more frequent, more severe, and longer-lasting.

According to the National Climate Assessment, "higher surface temperatures brought about by global warming increase the potential for drought. Evaporation and the higher rate at which plants lose moisture through their leaves both increase with temperature. Unless higher evapotranspiration rates are matched by increases in precipitation, environments will tend to dry, promoting drought conditions" (Globalchange.gov, 2014).

Because expected changes in precipitation patterns are still uncertain, the potential impacts and likelihood of drought are uncertain. DWR has noted impacts of climate change on statewide water resources by charting changes in snowpack, sea level, and river flow. As temperatures rise and more precipitation comes in the form of rain instead of snow, these changes will likely continue or grow even more significant. DWR estimates that the Sierra Nevada snowpack, which provides a large amount of the water supply for the Santa Clara County OA and other parts of the state, will experience a 48- to 65- percent loss by the end of the century compared to historical averages (DWR, 2016b). Increasing temperatures may also increase net evaporation from reservoirs by 15 to 37 percent (DWR, 2013). In addition to snowpack resources, the OA's water supply is derived from groundwater and surface water resources. increased incidence of drought may cause a drawdown in groundwater resources without allowing for the opportunity for aquifer recharge.

Exposure, Sensitivity and Vulnerability

POPULATION
Population exposure and vulnerability to drought are unlikely to increase as a result of climate change.

While greater numbers of people may need to engage in behavior change, such as water saving efforts, significant life or health impacts are unlikely.

PROPERTY
Property exposure and vulnerability may increase as a result of increased drought resulting from climate change, although this would most likely occur in non-structural property such as crops and landscaping.

It is unlikely that structure exposure and vulnerability would increase as a direct result of drought, although secondary impacts of drought, such as wildfire, may increase and threaten structures.

CRITICAL FACILITIES
Critical facility exposure and vulnerability are unlikely to increase as a result of increased drought resulting from climate change; however, critical facility operators may be sensitive to changes and need to alter standard management practices and actively manage resources, particularly in water-related service sectors.

ENVIRONMENT
The vulnerability of the environment may increase as a result of increased drought resulting from climate change. Ecosystems and biodiversity in the Bay Area are already under stress from development and water diversion activities. Prolonged or more frequent drought resulting from climate change may further stress the ecosystems in the region, which include many special status species.

ECONOMY
Increased incidence of drought could increase the potential for impacts on the local economy. Increased drought may impact the wine industry and related tourism activities. 264 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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EARTHQUAKE
Climate Change Impacts on the Hazard
The impacts of global climate change on earthquake probability are unknown. Some scientists say that melting glaciers could induce tectonic activity. As ice melts and water runs off, tremendous amounts of weight are shifted on the earth's crust. As newly freed crust returns to its original, pre-glacier shape, it could cause seismic plates to slip and stimulate volcanic activity, according to research into prehistoric earthquakes and volcanic activity. NASA and USGS scientists found that retreating glaciers in southern Alaska may be opening the way for future earthquakes (NASA, 2004).

Secondary impacts of earthquakes could be magnified by climate change. Soils saturated by repetitive storms or heavy precipitation could experience liquefaction or an increased propensity for slides during seismic activity due to the increased saturation. Dams storing increased volumes of water due to changes in the hydro graph could fail during seismic events.

Exposure, Sensitivity and Vulnerability
Because impacts on the earthquake hazard are not well understood, increases in exposure and vulnerability of the local resources are not able to be determined.

FLOOD
Climate Change Impacts on the Hazard
Use of historical hydrologic data has long been the standard of practice for designing and operating water supply and flood protection projects. For example, historical data are used for flood forecasting models and to forecast snowmelt runoff for water supply. This method of forecasting assumes that the climate of the future will be similar to that of the period of historical record. However, the hydrologic record cannot be used to predict changes in frequency and severity of extreme climate events such as floods. Scientists project greater storm intensity with climate change, resulting in more direct runoff and flooding. High frequency flood events (e.g. 10-year floods) in particular will likely increase with a changing climate. What is currently considered a l-percent-annual-chance (lOO-year flood) also may strike more often, leaving many communities at greater risk. Going forward, model calibration must happen more frequently, new forecast-based tools must be developed, and a standard of practice that explicitly considers climate change must be adopted.

Climate change is already impacting water resources, and resource managers have observed the following:
• Historical hydrologic patterns can no longer be solely relied upon to forecast the water future. • Precipitation and runoff patterns are changing, increasing the uncertainty for water supply and quality, flood management and ecosystem functions.
• Extreme climatic events will become more frequent, necessitating improvement in flood protection, drought preparedness and emergency response.

The amount of snow is critical for water supply and environmental needs, but so is the timing of snowmelt runoff into rivers and streams. Rising snowlines caused by climate change will allow more mountain areas, such as the Sierra Nevada watersheds, to contribute to peak storm runoff. Changes in watershed vegetation and soil moisture conditions will likewise change runoff and recharge patterns. As stream flows and velocities change, erosion patterns will also change, altering channel shapes and depths, possibly increasing sedimentation behind dams, and affecting habitat and water quality. With potential 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 265

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increases in the frequency and intensity of wildfires due to climate change, there is potential for more floods following fire, which increase sediment loads and water quality impacts.

Exposure, Sensitivity and Vulnerability

POPULATION AND PROPERTY
Population and property exposure and vulnerability may increase as a result of climate change impacts on the flood hazard. Runoff patterns may change, resulting in flooding in areas where it has not previously occurred.

CRITICAL FACILITIES
Critical facility exposure and vulnerability may increase as a result of climate change impacts on the flood hazard. Runoff patterns may change, resulting in risk to facilities that have not historically been at risk from flooding. Additionally, changes in the management and design of flood protection critical facilities may be needed as additional stress is placed on these systems. Planners will need to factor a new level of safety into the design, operation, and regulation of flood protection facilities such as dams, bypass channels and levees, as well as the design of local sewers and storm drains.

ENVIRONMENT
The exposure and vulnerability of the environment may increase as a result of climate change impacts on the flood hazard. Changes in the timing and frequency of flood events may have broader ecosystem impacts that alter the ability of already stressed species to survive.

ECONOMY
If flooding becomes more frequent, there may be impacts on the local economy. More resources may need to be directed to response and recovery efforts, and businesses may need to close more frequently due to loss of service or access during flood events.

LANDSLIDE
Climate Change Impacts on the Hazard
Climate change may impact storm patterns, increasing the probability of more frequent, intense storms with varying duration. Increase in global temperature is likely to affect the snowpack and its ability to hold and store water. Warming temperatures also could increase the occurrence and duration of droughts, which would increase the probability of wildfire, reducing the vegetation that helps to support steep slopes. All of these factors would increase the probability for landslide occurrences.

Exposure, Sensitivity and Vulnerability

POPULATION AND PROPERTY
Population and property exposure and vulnerability would be unlikely to increase as a result of climate change impacts on the landslide hazard. Landslide events may occur more frequently, but the extent and location should be contained within mapped hazard areas or recently burned areas.

CRITICAL FACILITIES
Critical facility exposure and vulnerability would be unlikely to increase as a result of climate change impacts on the landslide hazard; however, critical facility owners and operators may experience more frequent disruption to service provision as a result of landslide hazards. For example, transportation systems may experience more frequent delays if slides blocking these systems occur more frequently. In addition, increased sedimentation resulting from landslides may negatively impact flood control facilities, such as dams.
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ENVIRONMENT
Exposure and vuInerabiHty of the environment would be unlikely to increase as a result of climate change, but more frequent slides in river systems may impact water quality and have negative impacts on stressed species.

ECONOMY
Changes to the landslide hazard resulting from climate change are unlikely to result in impacts on the local economy.

SEVERE WEATHER
Climate Change Impacts on the Hazard
Climat e change presents a challeng e for risk management associated with severe weather. The number of weather -related disasters during the 1990s was four times that of the 1950s and led to 14 times as much in economic losses. The science for linking the severity of specific severe weather even ts to climate change is still evolving; howe er, a number or trends provide some indication of how climate change may be impacting these events. According to the U.S. National Climate Change Assessment (2014), there were more than twice as many high temperature records as low temperature records broken betw een 2001 and 2012, and heavy rainfall events are becoming more frequent and more severe.

The increase in average surface temperatures can also lead to more intense heat waves that can be exacerbated in urbanized areas by what is known as the urban heat island effect. Evidence suggests that heat waves are already increasing, especially in western states . Extreme heat days in the OA are likely to increase.

Climate change impacts on other severe weather events such as thunderstorms and fog are still not well understood . .

Exposure, Sensitivity and Vulnerability

POPULATION AND PROPERTY
Population and property exposure and vulnerability would be unlikely to increase as a direct result of climate change impacts on the severe weather hazard. Severe weather events may occur more frequently, but expos ure and vulnerability will remain the same. Secondary impacts, such as the extent of localized flooding, may increase, impacting greater numbers of people and structures.

CRITICAL FACILITIES
Critical facility exposure and vulnerability would be unlikely to increase as a result of climate change impacts on the severe weather hazard; how ever, critical facility owners and operators may experience more freq uent disru ption to service provision . For example, more frequent and intense storms may cause more frequent disruptions in power service.

ENVIRONMENT
Exposure and vulnerability of the environm ent would be unlikely to increase; however, more frequent storms and heat events and more intense rainfall may place additional stressors on already stressed systems.

ECONOMY
Climate change impacts on the severe weather hazard may impact the local economy through more frequent disruption to services, such as power outages. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 267

TSUNAMI
Climate Change Impacts on the Hazard

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The impacts of global climate change on tsunami probability are unknown. Some scientists say that melting glaciers could induce tectonic activity, inducing earthquakes. Other scientists have indicated that underwater avalanches (also caused by melting glaciers), may also result in tsunamis. Even if climate change does not increase the frequency with which tsunamis occur, it may result in more destructive waves. As sea levels continue to rise, tsunami inundation areas would likely reach further into communities than current mapping indicates.

Exposure, Sensitivity and Vulnerability
As land area likely to be inundated by tsunami waves increases, exposure and vulnerability to the tsunami hazard may increase for population, property, critical facilities and the environment.

Changes to the tsunami hazard from climate change may result in more direct economic impacts on a greater number of businesses and economic centers, as well as the infrastructure systems that support those businesses.

WILDFIRE
Climate Change Impacts on the Hazard
Wildfire is determined by climate variability, local topography, and human interVfmtion. Climate change has the potential to affect multiple elements of the wildfire system: fire behavior, ignitions, fire management, and vegetation fuels. Hot dry spells create the highest fire risk. Increased temperatures may intensify wildfire danger by warming and drying out vegetation.

Changes in climate patterns may impact the distribution and perseverance of insect outbreaks that create dead trees (increase fuel). When climate alters fuel loads and fuel moisture, forest susceptibility to wildfires changes. Climate change also may increase winds that spread fires. Faster fires are harder to contain, and thus are more likely to expand into residential neighborhoods.

Exposure, Sensitivity and Vulnerability

POPULATION
According to Cal-Adapt projections, wildfire risk in the areas surrounding the OA may actually decrease over the next century. Other areas of California and the western United States are expected to have increased risk to wildfire, with increases in annual acres burned. Although OA residents may not experience increased risk to wildfire directly, secondary impacts, such as poor air quality may increase.

PROPER7Y AND CRITICAL FACILITIES
If wildfire risk decreases, the exposure and vulnerability of property and critical facilities would remain the same.

ENVIRONMENT
It is possible that the exposure and vulnerability of the environment will be impacted by changes in wildfire risk due to climate change. Natural fire regimes may change, resulting in more or less frequent or higher intensity burns. These impacts may alter the composition of the ecosystems in areas in and surrounding the OA.
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ECONOMY
As the risk from wildfire is currently projected to decrease, direct impacts on the economy would not be likely.

VULNERABILITY ASSESSMENT-SEA LEVEL RISE

CLIMATE CHANGE IMPACTS ON THE HAZARD
In addition to impacts on the identified hazards of concern, climate change presents risks related to sea level rise. Sea level rise will cause currently dry areas to be permanently inundated; temporary inundation from extreme tide events and storm surge also will change. Unlike many other impacts resulting from climate change, sea level rise will have a defined extent and location. Although the extent and timing of sea level rise is still uncertain, conducting an assessment of potential areas at risk provides information appropriate for planning purposes.

EXPOSURE, SENSITIVITY AND VULNERABILITY
The following assessment was conducted using data provided by the San Francisco Bay Conservation and Development Commission. A sea level rise of 77 inches above current mean higher high water was assumed.

Population
Sea level rise will increase the population exposed to both permanent and temporary inundation.

Currently, approximately 1.2 percent of the OA population is estimated to reside in areas subject to sea level rise impacts. The vast majority of these individuals reside in Palo Alto. Table 14-2 shows exposed population by jurisdiction.

TABLE 14-2. ESTIMATED POPULATION RESIDING IN SEA LEVEL RISE INUNDATION AREAS JUrisdiction Estimated Po ulatlon Estimated Po ulation Ex osed % of Po ulation Ex osed Campbell 42,584 !O 0.0%
Cupertino 58,185 0 0.0%
Gilroy 55,170 0 0.0%
Los Altos 31 , ~53 0 0.0%
Los Altos Hills 8,658 0 0.0%
Los Gatos 31.3?6 0 0.0%
Milpitas 75.521 2,691 3.6%
Monte Sereno 3,475 0 0.0%
Morgan Hill 43,645 0 0.0%
Mountain View 77,925 27 0.0%
Palo Alto 68,207 13,685 20.1%
San Jose 1,042,094 3.529 0.3%
Santa Clara (city) 123,752 1,791 1.4%
Saratoga 30.219 0 0.0%
Sunnyvale 148.372 634 0.4%
Unincorporated County 87352 5 0.0%
Total 1927,888 22361 ttmA
10/15/17 Santa Clara County Operational Area Mitigation Pian Page I 269 Property

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There are 6,469 structures within the sea level rise inundation areas, about 88 percent of them residential.

This represents about 4 percent of the OA's total replacement value. Table 14-3 shows the distribution of structure types exposed and Table 14-4 shows the estimated replacement value of exposed structures.

The majority of these assets are in Sunnyvale, San Jose and Palo Alto.

TABLE 14-3. STRUCTURE TYPE IN SEA LEVEL RISE INUNDATION AREAS Junsdictlon Residential Commercial Industnal A ncultural ReI! IOUS Government I Education Total Campbell 0 0 0 0 0 0 0 0
Cupertino 0 0 0 10 iO 0 0 0
Gilroy 0 0 0 0 iO 0 0 0
Los Altos ,0 0 0 0 :0 0 '0 0
Los Altos Hills 0 0 0 0 ]0 0 0 0
Los Gatos 0 0 0 0 0 0 0 0
Milpitas '620 10 4 0 i1 0 0 835
Monte Sereno 0 0 0 0 0 0 !O 0
Morgan Hill 0 0 0 0 io 0 0 0
Mountain View 6 53 42 0 ,0 ,0 102
Palo Alto :3,799 129 71 0 ;7 0 8 4.014
San Jose 767 111 26 0 '6 0 2 912
Santa Clara (city) 390 32 28 0 iO 0 0 480
Saratoga 0 0 0 0 iO 0 0 0
Sunnyvale 130 66 157 ;1 0 0 355
0 ,0 0 :0 0 0 1

32.8 1 16 1 10 6469,
TABLE 14-4. STRUCTURE AND CONTENTS VALUE IN SEA LEVEL RISE INUNDATION AREAS J d t Structures Estimated Value ofl Estimated Value of Estimated Total I % of Total UriS Ie Ion Ex osed Ex osed Structures Ex osed Contents Value Re lacement Value Campbell 0 $0 $0 $0 0,0%
Cupertino 0 $0 $0 $0 0.0%
Gilroy :0 $0 $0 $0 0.0%
Los Altos 0 $0 $0 $0 0.0%
Los Altos Hills 0 $0 $0 1$0_ 0.0%
Los Gatos 0 $0 $0 $0 0.0%
Milpitas 635 $468,554.661 $386,407,648 $854,962.309 4.5% Monte Sereno 0 $0 $0 $0 0.0%
lVIorg,an Hili 0 $0 $0 $0 0.0%
Mountain View 102 $1 ,012,240,021 $1 ,110,560,396 $2,122,800,417 8.5% Palo Alto 4,014 $2,069.879,805 $1,642,022,511 $3,7 11 , 902 .~16 14.4% San Jose 912 $2 l57~ , 15_2 l96~ : $2,275.265.284 $4,848,418,248 2.3% Santa ~Iara (city) 450 $1 ,273,778,027 i $1 ,228,024,465 $2,501,802,492 5.8% Saratoga 0 $0 $0 1$0 0.0%
Sunnr!ale 355 $2,632,745,163 $3,074,816.827 1$5,707,561,990 13.3% 270 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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J d t Structures Estimated Value of Estimated Value of Estimated Total : % of Total uns IC Ion Ex osed Ex osed Structures Ex osed Contents Value ,Re lacement Value Unincorporated
Count
Total 646.9
Critical Facilities
$262,260
$10.030.612.900
$131,130
$9.717f 228.260
$393,390 0.0%
$197478411'62 4.1%
There are 185 critical facilities (5 percent of the total) located in OA areas subject to impacts from sea level rise. The majority of these facilities are infrastructure lifeline related facilities (65 percent) in Table 14-5.

TABLE 14-5. CRITICAL FACILITIES IN SEA LEVEL RISE INUNDATION AREAS I Emergency I :

J d t R / P bl Infrastructure Military Recovery Socioeconomic Hazardous Ttl UriS IC Ion I esponse u IC 0 a Health & Safet Lifeline FaCilities FaCIlities FaCilities Matenals Campbell 0 0 0 0 0 0 0
Cuperti~o 0 0 0 0 0 0 0
Gilroy 0 0 0 0 0 0 0
Los Altos 0 0 0 0 0 0 0
Los Altos Hills 0 10 0 0 0 0 0-
Los Gatos 0 0 0 0 0 0 0
Milpitas 0 J15 0 0 2 1 18
Monte Sereno '0 '0 0 0 0 0 0
Morgan Hill 0 10 0 0 0 0 0
Mountain View ; 13 ,0 0 0 2 18
Palo Alto 0
i
,30 '0 0 15 5 50
San Jose 2 '25 ,0 0 5 7 39
SantaCI~. ra (city) : 0 119 0 0 4 8 31
Saratoga 0 10 \0 0 0 0 0
~unnyvale 18 :0 ;0 0 10 29
Unincorporated 0 '0 iO 0 2 County
TGtII 4 121 0 0 28 34 185
Environment
All sea level rise inundation areas are exposed and vulnerable to impacts. Important coastal habitat may be lost as sea level rise permanently inundates areas, or it may be damaged due to extreme tide and storm surge events. Saltwater intrusion into freshwater resources may occur, further altering habitat and ecosystems. Protective ecosystem services may be lost as land area and wetlands are permanently inundated.

Economy
Sea level rise will impact the local economy. The tourism industry may be impacted as historic coastal properties are inundated. Critical facilities and other important assets may be damaged by temporary inundation, resulting in loss of services such as power or wastewater treatment. Coastal businesses may relocate to other areas rather than face high costs from increased risk to storm surge and costs associated with managed retreat. Local tax revenue may decline as areas that were previously occupied by houses and businesses are permanently inundated.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page 1271 Future Development

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The land area of the OA will be reduced as sea level rise permanently inundates areas. This will have significant impacts on land use and planning in local communities. Local general plans in the OA will guide this future development.

ISSUES
The major issues for climate change are the following:
• Planning for climate change related impacts can be difficult due to inherent uncertainties in projection methodologies.
• Average temperatures are expected to continue to increase in the OA, which may lead to a host of primary and secondary impacts, such as an increased incidence of heat waves. • Expected changes in precipitation patterns are still poorly understood and could have significant impacts on the water supply and flooding in the OA. • Some impacts of climate change are poorly understood such as potential impacts on the frequency and severity of earthquakes, thunderstorms and tsunamis. • Heavy rain events may result in inland stormwater flooding after stormwater management systems are overwhelmed .
• Permanent and temporary inundation resulting from sea level rise has the potential to impact significant portions of the population and assets in the OA. 272 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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OTHER HAZARDS OF INTEREST

GENERAL BACKGROUND
In addition to the hazards of concern presented in the preceding chapters, four other hazards of interest were identified for inclusion in this plan:
• Intentional criminal, malicious acts, including acts of terrorism, cyber threats, and active threats.
• Technological incidents that arise accidentally from human activities such as the manufacture, transportation, storage and use of hazardous materials; transportation accidents; pipeline failure and release; and utility failure.
• Epidemics and pandemics of human disease.
• Fog
Although the DMA does not require an assessment of these hazards, the Working Group decided to include them in this hazard mitigation plan for the following reasons:
• This plan takes a proactive approach to disaster
preparedness to protect the public safety of all citizens. • Preparation for and response to an event involving these hazards of interest will involve many of the same staff, critical decisions, and commitment of resources as a natural hazard.
• The multi-hazard mitigation planning effort is an
opportunity to inform the public about all hazards, including those beyond the natural hazards of concern.
• The likelihood of an event involving one of these hazards of interest in the Santa Clara County OA is greater than some of the identified natural hazards in this plan.
• The planning partners participate with the Bay Area Urban Area Security Initiative, ensuring a regional capacity to prevent, protect against, respond to, and recover from
terrorist activities. The Santa Clara County Sheriff's
Department is a member agency of the South Bay Terrorism Early Warning Group (TEWG) to interdict terrorism in local communities.

DEFINITIONS
Terrorism-The unlawful use or
threatened use of force or violence
against people or property with the
intention of intimidating or coercing
societies or governments. Terrorism
is either foreign or domestic,
depending on the origin, base, and
objectives of the terrorist or
organization.

Technological Hazards-Hazards
from accidents associated with
human activities such as the
manufacture, transportation, storage
and use of hazardous materials.

Weapons of Mass Destruction­
Chemical, biological, radiological,
nuclear, and explosive weapons
associated with terrorism.

Hazardous Material-A substance or
combination of substances that,
because of quantity, concentration,
physical, chemical, or infectious
characteristics, may cause or
contribute to an increase in mortality
(liT an increase in serious irreversible
or incapacitating reversible illness, or
pGse a present or potential hazard to
human life, property, or the
envimnment.

Fog.- Visible cloud water droplets
that are low-lying and influenced by
nearby Podies of water, topography,
and Wind oondltlons.

This chapter summarizes available information on the identified hazards of interest. It profiles them, but they are not fully assessed and ranked like the primary hazards of concern. Mitigation actions for these hazards are not mandatory under 44 CFR Section §201.6(c)(2)(i)).

INTENTIONAL HAZARDS
Terrorism and Weapons of Mass Destruction
Terrorist activities are those that involve an illegal use of force, are intended to intimidate or coerce, and are committed in support of political or social objectives. FEMA defines terrorism as the use of weapons of mass destruction, including biological, chemical, nuclear and radiological weapons; arson, incendiary, 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 273

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explosive and armed attacks; industrial sabotage and intentional hazardous materials releases; agro­ terrorism; and cyber-terrorism (FEMA 386-7). The following are potential methods used by terrorists that could affect the OA as a direct target or collaterally:
• Bombings; improvised explosive • Conventional firearms j mass devices shootings
• Suicide attacks • Secondary attacks
• Chemical or biological weapons • Cyber-terrorism
• Radiological dispersal device • Agro-terrorism
• Vehicle j aircraft attacks • Kidnappingsj assassinations • Incendiary devicesj arson • Nuclear weapons (fission or thermonuclear)
Three important considerations distinguish terrorism hazards from other types of hazards:
• Terrorism evokes very strong emotional reactions, ranging from anxiety, to fear, to anger, to despair, to depression, which must be taken into consideration for planning. • There is limited scientific understanding of how some terrorist weapons, such as biological and radiological agents, affect the population at large. • In the case of biological and radiological agents, their presence may not be immediately obvious, making it difficult to determine when and where they may have been released, who has been exposed, and what danger is present for first responders and emergency medical technicians.

The Federal Bureau of Investigation (FBI) categorizes two types of terrorism in the United States:
• Domestic terrorism involves groups or individuals whose terrorist activities are directed at elements of our government or population without foreign direction. The bombing of the Alfred P. Murrah federal building in Oklahoma City is an example of domestic terrorism. The FBI is the primary response agency for domestic terrorism. The FBI coordinates domestic preparedness programs and activities of the United States to limit acts posed by terrorists including the use of weapons of mass destruction (WMDs). • International terrorism involves groups or individuals whose activities are foreign-based or directed by groups outside the United States, or whose activities transcend national boundaries. Examples include the 1993 bombing of the World Trade Center, the U.s. Capitol, and Mobil Oil's corporate headquarters and the attacks of September 11, 2001 at the World Trade Center and the Pentagon.

Those involved with terrorism response, including law enforcement, fire and rescue, public health and public information staff, are trained to deal with the public's emotional reaction swiftly as response to the event occurs. The area of the event must be clearly identified in all emergency alert messages to prevent those not affected by the incident from overwhelming local emergency rooms and response resources therefore reducing service to those actually affected. The public will be informed clearly and frequently about what government agencies are doing to mitigate the impacts of the event. The public will also be given clear directions on how to protect the health of individuals and families.

Table 15-1 provides a hazard profile summary for terrorism-related hazards. Most terrorist events in the United States have been involved detonated and undetonated explosive devices, tear gas, pipe bombs, and firebombs.
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TABLE 15-1. EVENT PROFILES FOR TERRORISM
IApplication Hazard StaticlDynamic Mitigating and Exacerbating Hazard a . b Ch .. C C d" d
Conventional
Bomb
Chemical
Agent
Arsonl
Incendiary
Attack
Armed Attack
10/15/17
Mode Duration aractenstlcs on ItlOns
Detonation of
explosive device
on or near target;
I
delivery via
person, vehicle,
or projectile.

Liquid/aerosol
contaminants
Instantaneous;
additional
secondary devices,
or diversionary
activities may be
used, lengthening
the duration of the
hazard until the
attack site is
determined to be
clear.
dispersed using Hours to weeks,
sprayers or other 'depending on the
aerosol agent and the
generators; . d'l: ' h' h
I"d .. con Idons In W IC IqUi S vaporizing l . t
from puddles/ ,I eXls s.
containers; or
munitions.

Initiation of fire or
I explosion on or
I near target via
direct contact or
remotely via
projectile.

Tactical assault
or sniping from
remote location,
or random attack
based on fear,
emotion, or
mental instability.

Generally minutes
to hours.

Generally minutes
to days.

Extent of damage is determined by
type and quantity of explosive.

Effects generally static other than
cascading consequences,
incremental structural failure, etc.

Overpressure at a given standoff is
inversely proportional to the cube of the
distance from the blast; thus, each
additional increment of standoff provides
progressively more protection. Terrain,
forestation, structures, etc. can provide
shielding by absorbing and/or deflecting
energy and debris. Exacerbating
conditions include ease of access to
target; lack of barriers and shielding; poor
construction; and ease of concealment of
device.

Air temperature can affect evaporation of
aerosols. Ground temperature affects
evaporation of liquids. Humidity can
Contamination can be carried out enlarge aerosol particles, reducing of the initial target area by persons, ~:da ~~~~~:Z:~~~~;~~f~:~osnp~:;d dilute vehicles, water, and wind. . contamination. Wind can disperse vapors Chemicals may be corrosive or otherwise damaging over time if but also cause target area to be dynamic. not remediated. The micro-meteorological effects of
buildings and terrain can alter travel and
duration of agents. Shielding in the form of
sheltering in place can protect people and
property from harmful effects.

Extent of damage is determined by
type and quantity of device,
accelerant, and materials present
at or near target. Effects generally
static other than cascading
consequences, incremental
structural failure, etc.

Va.ries based on the perpetrators'
intent and capabilities.

Mitigation factors include built-in fire
detection and protection systems and fire­
resistive construction techniques.

Inadequate security can allow easy
access to target, easy concealment of an
incendiary device, and undetected
initiation of a fire. Non-compliance with fire
and building codes, as well as failure to
maintain existing fire protection systems,
can substantially increase the
effectiveness of a fire weapon.

Inadequate security can allow easy
access to target, easy concealment of
weapons, and undetected initiation of an
attack.

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H d Application I Hazard Static/Dynamic Mitigating and Exacerbating azar . . . . . Mode a Duratlon b Characterlstlcs C Condltlons d Biological
Agent
Agro-terrorism
Radiological
Agent
,
I Liquid or solid
contaminants
dispersed using , H t / I ' ours 0 years, sprayers aeroso : depending on the generators or by . t d th . t r . agen an e
pOin or Ine : conditions in which
sources such as ·t . t
munitions, covert : I eXls s.
deposits, and
moving sprayers . .

Direct, generally
covert
contamination of
food supplies or
introduction of Days to months.
pests and/or
disease agents to
crops and
livestock.

Radioactive
contaminants
dispersed using
sprayers/ aerosol
generators, or by
point or line
: sources such as
• munitions.

Detonation of
nuclear device
Seconds to years,
depending on
material used.

Nuclear Bomb . ~hned:~~~~~,~ 'n at
the air, or at high
altitude.

Light/heat flash and
blast/shock wave
last for seconds;
nuclear radiation
and fallout hazards
can persist for
years.

Electromagnetic
pulse from a high­
altitude detonation
lasts for seconds
and affects only
unprotected
electronic systems.

Altitude of release above ground can
Depending on the agent used and affect dispersion; sunlight is destructive to the effectiveness with which it is many bacteria and viruses; light to deployed, contamination can be moderate wind will disperse agents but spread via wind and water. higher winds can break up aerosol clouds; Infection can spread via humans or the micro-meteorological effects of animals. buildings and terrain can influence
Varies by type of incident. Food
contamination events may be
, limited to specific distribution sites,
whereas pests and diseases may
spread widely. Generally no effects
on built environment.

Initial effects will be localized to
site of attack; depending on
meteorological conditions,
subsequent behavior of radioactive
contaminants may be dynamic.
aerosolization and travel of agents.

Inadequate security can facilitate
adulteration of food and introduction of
pests and disease agents to crops and
livestock.

Duration of exposure, distance from
source of radiation, and the amount of
shielding between source and target
determine exposure to radiation.

Initial light, heat, and blast effects Harmful effects of radiation can be of a subsurface, ground or air burst reduced by minimizing the time of are static and determined by the exposure. Light, heat, and blast energy device's characteristics and . decrease logarithmically as a function of employment; fallout of radioactive distance from seat of blast. Terrain, . contaminants may be dynamic, forestation, structures, etc. can provide depending on meteorological shielding by absorbing and/or deflecting conditions. ' radiation and radioactive contaminants.
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Application Hazard StaticlDynamic Mitigating and Exacerbating Hazard Mode a Duration b Characteristics C Conditions d Intentional Solid, liquid,
Hazardous and/or gaseous
Material contaminants
Release (fixed released from
facility or fixed or mobile
transportation) containers
Hours to days.

Chemicals may be corrosive or
otherwise damaging over time.

Explosion and/or fire may be
I subsequent. Contamination may
be carried out of the incident area
by persons, vehicles, water and
wind.

Weather conditions directry affect how the
hazard develops. The micro­
meteorological effects of buildings and
terrain can alter travel and duration of
agents. Shielding in the form of sheltering
in place can protect people and property
from harmful effects. Non-compliance with
fire and building codes, as well as failure
to maintain existing fire protection and
containment features, can substantially
increase the damage from a hazardous
materials release.
a. Application Mode-application mode describes the human acts or unintended events necessary to cause the hazard to occur. b. Duratio~uration is the length of time the hazard is present. For example, a chemical warfare agent such as mustard gas, if un­ remediated, can persist for hours or weeks under the right conditions. c. Dynamic or Static Characteristics-these characteristics of a hazard describe its tendency, or that of its effects, to either expand, contract, or remain confined in time, magnitude, and space. For example, the physical destruction caused by an earthquake is generally confined to the place in which it occurs, and it does not usually get worse unless aftershocks or other cascading failures occur; in contrast, a cloud of chlorine gas leaking from a storage tank can change location by drifting with the wind and can diminish in danger by dissipating over time.
d. Mitigation and Exacerbating Conditions-mitigating conditions are characteristics of the target and its physical environment that can reduce the effects of a hazard. For example, earthen berms can provide protection from bombs; exposure to sunlight can render some biological agents ineffective; and effective perimeter lighting and surveillance can minimize the likelihood of someone approaching a target unseen. In contrast, exacerbating conditions are characteristics that can enhance or magnify the effects of a hazard. For example, depressions or low areas in terrain can trap heavy vapors, and a proliferation of street furniture (trash receptacles, newspaper vending machines, mail boxes, etc.) can provide hiding places for explosive devices.

Source: FEMA 386-7
The effects of terrorism can include injuries, loss of life, property damage, or disruption of services such as electricity, water supplies, transportation, or communications. Effects may be immediate or delayed.

Terrorists often choose targets that offer limited danger to themselves and areas with relatively easy public access. Foreign terrorists look for visible targets where they can avoid detection before and after an attack, such as international airports, large cities, major special events, and high-profile landmarks.

In dealing with terrorism, the unpredictability of human beings must be considered. People with a desire to perform such acts may seek out targets of opportunity that may not fall into established lists of critical areas or facilities. First responders in the Santa Clara County OA train to respond not only to organized terrorism events, but also to random acts by individuals who may choose to harm others and destroy property. While education, heightened awareness, and early warning of unusual circumstances may deter terrorism, intentional acts that harm people and property are possible at any time. Public safety entities must react to the threat, locating, isolating, and neutralizing further damage and investigating potential scenes and suspects to bring criminals to justice.

Cyber Threats
A cyber threat is an intentional and malicious crime that compromises the digital infrastructure of a person or organization, often for financial or terror-related reasons. Such attacks vary in nature and are perpetrated using digital mediums or sometimes social engineering to target human operators. Generally, attacks last minutes to days, but large-scale events and their impacts can last much longer. As 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 277

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information technology continues to grow in capability and interconnectivity, cyber threats become increasingly frequent and destructive. In 2014, internet security teams at Symantec and Verizon indicated that nearly 1 million new pieces of malware - malicious code designed to steal or destroy information­ were created every day (Harrison, 2015).

Cyber threats differ by motive, attack type and perpetrator profile. Motives range from the pursuit of financial gain to political or social aims. Cyber threats are difficult to identify and comprehend. Types of threats include using viruses to erase entire systems, breaking into systems and altering files, using someone's personal computer to attack others, or stealing confidential information . The spectrum of cyber risks is limitless, with threats having a wide-range of effects on the individual, community, organizational, and national threat (FEMA, 2013).

This risk assessment includes cyber-attacks and cyberterrorism. The terms often are used interchangeably, though they are not the same. While all cyberterrorism is a form of cyber-attack, not all cyber-attacks are cyberterrorism.

CYBER-ATTACKS
Public and private computer systems are subject to a variety of cyber-attacks, from blanket malware infection to targeted attacks on system capabilities. Cyber-attacks seek to breach IT security measures designed to protect an individual or organization. The initial attack is followed by more severe attacks for the purpose of causing harm, stealing data, or financial gain. Organizations are prone to attacks that can be either automated or targeted. Table 15-2 describes the most common cyber-attack mechanisms faced by organizalions today.

TABLE 15-2. COMMON MECHANISMS FOR CYBER Arr ACKS
Type Descri pti on
Socially E' d Programs designed to mimic legitimate processes (e.g. updating software, running fake antivirus software) with ngmeere the end goal of human-interaction caused infection. When the victim runs the fake process, the Trojan is Trojans installed on the system.
, Nearly all software has weak points that may be exploited by malware. Most common software exploitations Unpatched Software occur with Java, Adobe Reader, and Adobe Flash. These vulnerabilities are often exploited as small amounts of malicious code are often downloaded via drive-by download.

Phishing
Password Attacks
Malicious email messagesthataskuserstoclickalinkordownloadaprogram.Phishing attacks may appear as legitimate emails from trusted third parties.

Third party attempts to crack a user's password and subsequently gain access to a system. Password attacks do not typically require malware, but rather stem from software applications on the attacker's system. These applications may use a variety of methods to gain access, including generating large numbers of generated guesses, or dictionary attacks, in which passwords are systematically tested against all of the words in a dictionary.

Drive-by Downloads Malware is downloaded unknowingly by the victims when they visit an infected site.

Denial of Service Attacks that focus on disrupting service to a network in which attackers send high volumes of data until the Attacks network becomes overloaded and can no longer function.

Man in the Middle
Malvertlsing
Man-in-the-Middle attacks mirror victims and endpoints for online information exchange. In this type of attack, the attacker communicates with the victims, who believe they are interacting with a legitimate endpoint website. • The attacker is also communicating with the actual endpoint website by impersonating the victim. As the process goes through, the attacker obtains entered and received information from both the victim and endpoint.

Malware downloaded to a system when the victim clicks on an affected ad.

Advanced Persistent An attack in which the attacker gains access to a network and remains undetected. APT attacks are designed to Threat (APT) steal data instead of cause damage.

Source: Danie/son, 2015
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With millions of threats created each day, the importanc e of protection against cyber-atta cks becomes a necessary function of everyday operations for individuals, government facilities, and businesses. The increasing dependency on technology for vital information storage and the often automated method of infection means higher stakes for the success of measurable protection and education.

Since 2013, a new type of cyber-attack is becoming increasingly common against individuals and small­ and medium-sized organizations . This attack is called cyber ransom. Cybe r ransom occurs when an individual downloads ransom malware, or ransomware, often through phishing or dTive-by download, and the subsequent execution of code results in encryption of all data and personal files stored on the system. The victim then receives a message that demands a fee in the form of electronic currency or cryptocurrency, such as Bitcoin, for the decryption code (see Figure 15-1). In October 2015, the FBI said that commonly used ransomware is so difficult to override, that victims should pay the ransom to retrieve their data (Danielson, 2015).

Show1lt1c1
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t . r t
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http: // r6hq2tiq2h4~j.2kJ18.net
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YoU rrut hstalllhis browser w .... w "lOrofo)8CtOfg/pro)!!CtS/tprbrowser.html.en AfU" rnsta~.nrI 1te troweer and enter acb-ess 34rfihq2tiq2h4Jzj.onion Foltr. ltte ~tlC1l a'I tie wetH.I.. We remnd you ilat Ihe sooner you do !o, the men chaR;ss are left tD retOWll' \he flies.
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FIGURE 15-1. Pop-UP MESSAGE INDICATING RANSOMWARE INFECTION 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 279

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CYBERTERRORISM
Cyberterrorism is the use of computers and information, particularly over the Internet, to recruit others to an organization's cause, cause physical or financial harm, or cause a severe disruption of infrastructure service. Such disruptions can be driven by religious, political, or other motives. Like traditional terrorism tactics, cyberterrorism seeks to evoke very strong emotional reactions, but it does so through information technology rather than a physically violent or disruptive action. Cyberterrorism has three main types of objectives (Kostadinov, 2012):
• Organizational- cyberterrorism with an organizational objective includes specific functions outside of or in addition to a typical cyber-attack. Terrorist groups today use the internet on a daily basis. This daily use may include recruitment, training, fund raising, communication, or planning . Organizational cyberterrorism can use platforms such as social media as a tool to spread a message beyond country borders and instigate physical forms of terrorism.

Additionally, organizational goals may use systematic attacks as a tool for training new members of a faction in cyber warfare.
• Undermining- cyberterrorism with undermining as an objective seeks to hinder the normal functioning of computer systems, services, or websites. Such methods include defacing, denying, and exposing information. While undermining tactics are typically used due to high dependence on online structures to support vital operational functions, they typically do not result in grave consequences unless undertaken as part of a larger attack. Undermining attacks on computers include the following (Waldron, 2011):
.:. Directing conventional kinetic weapons against computer equipment, a computer facility, or transmission lines to create a physical attack that disrupts the reliability of equipment. .:. Using electromagnetic energy, most commonly in the form of an electromagnetic pulse, to create an electronic attack against computer equipment or data transmissions. By overheating circuitry or jamming communications, an electronic attack disrupts the reliability of equipment and the integrity of data .
• :. Using malicious code directed against computer processing code, instruction logic, or data.

The code can generate a stream of malicious network packets that disrupt data or logic by exploiting vulnerability in computer software, or a weakness in computer security practices.

This type of cyber-attack can disrupt the reliability of equipment, the integrity of data, and the confidentiality of communications (Wilson, 2008).
• Desrructiv e - the destructiv e objective for cyberterrorism is what organizations fear most.

Tluough the use of computer tedmology and the Internet, the terrorists seek to inflict destru ction or damag e on tangible property or assets, and even death or injury to individuals.

There are no cases of pure cybert errorism as of the date of this plan.

Active Threats

ACTIVE SHOOTER
Active shooter attacks are typically motivated by the desire to maximize human . casualties. They are differentiated from other attack typ es by the indiscriminate nature of the victims, who often are targets of opportunity. Active shooter attacks range from "lone wolf" shooters who act alone and without any organizational affiliation to organized groups acting in concert to achieve a specific objective. Active 280 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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shooter tactics sometimes employ a blend of lone shooters and multi-person tearns as part of a larger assault.

Active shooters may use small arms, light weapons, or a combination of the two depending on the type of attack. Small arms are revolvers, automatic pistols, rifles, shotguns, assault rifles, light machine guns, etc. Light weapons are medium caliber and explosive ordinance, grenade launchers, rocket propelled grenades, etc. Attackers can increase their likelihood of success by using a wider array of weapons, including improvised explosive devices.

BIOLOGICAL THREATS
Biological hazards include disease-causing microorganisms and pathogens, such as bacteria and viruses, that multiply within a host and cause an infection. Some bacteria and viruses can spread from one individual to another. Infections typically occur as a result of airborne exposure, skin contact, or ingestion.

In general, exposure to bacteria and viruses can occur through inhalation (as is the case with airborne B. anthracis spores, which cause anthrax), ingestion of contaminated food or water (the case with E. coli, which causes gastrointestinal infection), contact with infected individuals, or contact with contaminated surfaces (which may be harboring, for example, viruses that cause influenza). Domestic and transnational threat groups have considered targeting heating, ventilation, and air conditioning systems of large commercial buildings.

Anthrax has been used as a weapon for nearly 100 years and is one of the most likely agents to be used in a biological threat. Its spores are easily found in nature, can be produced in a lab, and can last for a long time. It can be released quietly and without anyone knowing. Microscopic spores can be put into powders, sprays, food, and water. Due to their size, victims may not be able to see, smell or taste them (CDC, 2016). Terrorists may release anthrax spores in public places. In 2001, letters containing powdered anthrax spores were sent through the U.S. mail, causing skin and lung anthrax in 22 people. Five people died, all due to lung anthrax (San Francisco Department of Health, 2016).

If a biological attack were to occur in the Santa Clara County OA, a large number of personnel could be impacted . Buildings in the impacted area and transportation infrastructure might be closed for investigation and cleanup. These areas would not be accessible until cleanup is completed, which would impact the businesses. Hospitals could become overwhelmed with people coming in fearing contamination. Residents and businesses may need to shelter in place in the area of the attack.

CHEMICAL THREATS
Chemical weapons are poisonous vapors, aerosols, liquids, and solids that have toxic effects on humans, animals, and plants. Exposure pathways include inhalation, skin contact, ingestion or injection.

Depending on the severity of exposure, impacts may include temporary illness or injury, permanent medical conditions, or death. An attack using chemical threats can come without warning. Signs of a chemical release include difficulty breathing; eye irritation; losing coordination; nausea; or a burning sensation in the nose, throat and lungs (Ready.gov, 2016b). Harmful chemicals that could be used in an attack include the following (U.s. Department of Homeland Security, 2004):
• Chemical weapons developed for military use (warfare agents). • Toxic industrial and commercial chemicals that are produced, transported, and stored in the making of petroleum, textiles, plastics, fertilizers, paper, foods, pesticides, household cleaners, and other products.
• Chemical toxins of biological origin such as ricin.
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Recently, there have been reports of chlorine found in explosive devices, mortars, rockets, and missiles.

Chlorine has been used in the past, mainly in blunt, terrorist-style attacks. Some experts believe that grou,ps are trying to advance their technology for deploying the chemical in combat operations (Tilghman, 2015). Chlorine is an acutely toxic industrial compound that can cause severe coughing, pulmonary, eye and skin irritation, and even death at higher concentrations (USACHPPM, 2015).

A chemical release in the Santa Clara County OA could lead to closure of streets and major transportation routes (including bridges) for extended periods of time, causing transportation delays and traffic. Many homes and businesses would also be impacted as they would need to be evacuated for an extended period of time. There could also be impact on the envirorunent and/or natural resources that would require cleanup. Hazardous material response teams and fire-rescue would be needed to respond to the incident and coordinate cleanup efforts.

EXPLOSIVE DEVICES
Improvised explosive device (lED) attacks are a favored method of terrorist groups around the world.

The evolution in explosive materials and firing devices and their ease of concealment and delivery have increased the effectiveness of this hazard. lED attacks are typically motivated by the desire to maximize human casualties. Explosive incidents account for 70 percent of all terrorist attacks worldwide. These types of attacks range from small-scale letter bombs to large-scale attacks on specific buildings.

According . to the FBI, 172 improvised explosive devices were reported in the United States between October 2012 and April 2013.

IEDs generally consist of TNT equivalent explosives (e.g. black or smokeless powder) in a container (e.g. galvanized pipe, paint can, etc.). These propellants are easily purchased on the commercial market. IEDs may also contain added shrapnel to induce greater casualties or shaped charges that direct the force of the explosive toward the target. Devices may be hidden in everyday objects such as briefcases, flowerpots or garbage cans, or on the person of the attacker in the case of suicide bombers. The most commonly used container is galvanized pipe, followed by PVC pipe. When shrapnel is added to the device, the type of shrapnel varies- BBs and other small pieces of hardware are common, as are glass and gravel.

An attack using IEDs or other explosive device in the Santa Clara County OA has potential large-scale consequences that may require multi-agency and multi-jurisdictional coordination. Depending on the location of the attack, businesses and other venues may be closed for investigation and due to damage.

If the attack occurred in or near residences, evacuations and/ or sheltering may occur.

FIRE AS A WEAPON
The use of fire for criminal, gang, and terrorist activities, as well as targeting first responders, is not new.

The World Health Organization estimates that 195,000 people die each year from fire. According to the Global Terrorism Database, an average of 7,258 people die annually from terrorism, and that includes deaths in conflict zones such as Afghanistan and Iraq (Stewart, 2013).

TECHNOLOGICAL HAZARDS
Technological hazards are associated with human activities such as the manufacture, transportation, storage and the use of hazardous materials. Incidents related to these hazards are assumed to be accidental with unintended consequences. Technological hazards can be categorized as follows:
• Hazardous materials incidents.
• Transportation incidents.
• Pipeline and tank hazards.
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• Utility failure.

Hazardous Materials Incidents
A hazardous material is any substance that is flammable, combustible, corrosive, poisonous, toxic, explosive or radioactive. Hazardous materials are present across the United States in facilities that produce, store, or use them. For example, water treatment plants use chlorine on-site to eliminate bacterial contaminants, and dry cleaning businesses may use solvents that contain perchloroethylene.

Even the natural gas used in homes and businesses is a dangerous substance when a leak occurs.

Hazardous materials are transported along interstate highways and railways daily. The following are the most common types of hazardous material incidents:
• Fixed-Facility Hazardous Materials Incident-This is the uncontrolled release of materials from a fixed site capable of posing a risk to health, safety and property. It is possible to identify and prepare for a fixed-site incident because laws require those facilities to notify state and local authorities about what is being used or produced at the site. • Hazardous Materials Transportation Incident- This is any event resulting in uncontrolled release during transport of materials that can pose a risk to health, safety, and property.

Transportation incidents are difficult to prepare for because there is little if any notice about what materials could be involved should an accident happen. These incidents can occur anywhere, although most occur on major federal or state highways or major rail lines. In addition to materials such as chlorine that are shipped throughout the country by rail, thousands of shipments of radiological materials (mostly medical materials and low-level radioactive waste) take place via ground transportation across the United States. Many incidents occur in sparsely populated areas and affect few people. However, hazardous materials have been involved in accidents in areas with much higher population densities, such as the January 6, 2005 train accident in Graniteville, South Carolina that released chlorine gas killing nine, injuring 500, and causing the evacuation of 5,400 residents. • Pipeline Hazardous Materials Incident-Numerous natural gas pipelines, heating oil, and petroleum pipelines run through the Santa Clara County OA and surroundings. These are used to provide these products to utilities in the region and to transport the materials from production facilities to end users.

Federal regulations govern the transportation of hazardous materials in all modes of transportation: air, highway, rajl and water (Title 49, Code of Federal Regulations; Transportation, Code of Federal Regulations, Hazardous Materials Regulations). Title 49 CFR lists thousands of hazardous materials, including gasoline, insec ticides, household cleaning products, and radioactive materials. California regulated substances that have the greatest probability of adversely impacting the community are listed in state code (Title 19, Division 2, Chapter 4.5, Sections 2735-2785; Hazardous Material Management Plan/Hazardous Material Inventory).

Santa Clara County has four Certified Unified Program Agencies that administer hazardous materials, hazardous waste and underground storage tank programs within their jurisdictions. • Hazardous Materials Compliance Division of the Santa Clara County Department of Environmental. Health (for all areas of Santa Clara County other than the cities of Santa Clara, Gilroy, and Sunnyvale).
• Santa Clara City Fire Department.
• Gilroy Building, Life and Environmental Safety.
• Sunnyvale Department of Public Safety.
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Participating Agencies are local fire agencies that coordinate their activities under a memorandum of understanding with Santa Clara County Department of Environmental Health:
• Milpitas Fire Department.
• Mountain View Fire Department.
• Palo Alto Fire Department.
• Santa Clara County Fire Department.

Transportation Incidents
Transportation incidents are those involving air, road or rail travelers resulting in death or serious injury.

The potential for transportation accidents that block movement through the OA is significant, as is the likelihood of hazardous material incidents resulting from a traffic or rail accident.

The Bay Area has a number of airports, induding the San Francisco International Airport, Oakland International Airport, and San Jose International Airport, as well as San Martin Airport and Reid Hillview Airport, which are smaller municipal airports that enhance the potential for an air disaster.

Major transportation routes in the OA include the following:
• Major highways include Interstates 880 (Nimitz Freeway) and 280; U.s. Highway 101 and Highway 237; and State Routes 87, 85, and 17.
• 42.2 miles of light rail serving Santa Clara County is operated by the Santa Clara Valley Transportation Authority (VTA), which oversees public transit services in the county. The Santa Clara VT A is continuing development for Phase II of its BART Silicon Valley Extension.

The project planning includes a 5.1-mile-Iong subway tunnel through downtown San Jose and four additional stations, at Alum Rock, Downtown San Jose, Diridon, and Santa Clara.

Construction of Phase II is anticipated to begin as additional funding is secured in 2019, based on the preliminary schedule (Santa Clara VTA, 2017).
• Amtrak has a train station in San Jose at Santa Clara University. • The Santa Clara Depot, in the City of Santa Clara, is served by the Cal train from San Francisco and the Altamont Corridor Express from Stockton.
• The Great America station in the City of Santa Clara hosts Amtrak's Capitol Corridor trains and Altamont Corridor Express trains. The station is close to Levi's Stadium and California's Great America.
• There are 15 Cal train stations in the OA. Caltrain is a commuter rail between San Francisco, San Mateo and Santa Clara counties.
• The Santa Fe railroad has a right of way that parallels U.s. Highway 101 through the eastern edge of the county.
• Daily commuter traffic is very high in the OA due to Silicon Valley's dense-employment population.

Pipeline Hazards

PIPELINE SYSTEMS AND RISKS
Around 1945, the United States invested in the development of a nation-wide system of pipelines for the purpose of transporting natural gas and petroleum products. The majority of these materials are moved by hazardous liquid and gas transport operators through a system of pipelines ranging in diameter from 20 to 42 inches. These pipes reach from the material origin wells to their final destination in refineries that further process the material for use and transport over 50 percent of the United States' energy supply.

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petroleum products, and chemical products, there is still an inherent risk due to the nature of the hazardous materials.

Transmission pipelines are those that transport raw material for further refinement. These pipes are large and far reaching, operating under high pressure. Distribution pipelines are those that provide processed materials to end users. These are smaller in diameter, some as small as a half an inch, and operate under lower pressure. Failures of distribution and transmission pipelines can occur when pipes corrode, are damaged during excavation, are incorrectly operated, or are damaged by other forces. More serious accidents occur on distribution pipelines than on any other type due to their number, intricate networking, and location in highly populated areas.

The greatest risk to the public regarding pipelines is the unintended release of a material being transported through the system. These materials are hazardous and have the capability to severely impact the surrounding environment, population, and property. These impacts may lead to severe injury or death. Combustible material transported through these pipelines may ignite or explode. Hazardous liquids may contaminate water systems. Families that rely on the transported material to heat their households may experience disruption of service. Pipeline failures also have the potential to negatively impact the economy, causing business interruptions or severely damaging vital infrastructure.

Depending on the pipeline material, age of the system, and transported product, pipelines may experience one or more general types of corrosion. Table 15-3 identifies corrosion types and a description of each.

TABLE 15-3. CORROSION TYPES
Corrosion
T DeSCription ype
External
Internal
External corrosion occurs due to environmental conditions on the outside of the pipe.

Corrosion on the internal wall of a natural gas pipeline can occur when the pipe wall is exposed to water and contaminants in the gas, such as 02, H2S, C02, or chlorides.

Atmospheric Atmospheric corrosion occurs on a steel surface in a thin wet film created by the humidity in the air in combination with . !mpurities.

Stress Stress corrosion cracking is the initiation of cracks and their propagation, possibly up to complete failure of a Cracking component, due to the combined action of tensile mechanical loading and a corrosive medium.

Source: PHMSA, 2011
Pipeline material plays an important role in the possibility of experiencing a pipeline failure. Between 2006 and 2010, for both hazardous liquid and gas transmission pipelines, the main causes for failure were corrosion, material or welding failure, or damage due to excavation (PHMSA, 2011). Plastic pipes installed for natural gas distribution systems from the 1960s through the early 1980s may be vulnerable to cracking, resulting in gas leakage and potential hazards to the public. Hundreds of thousands of miles of plastic pipe have been installed, with a significant amount installed prior to the mid-1980s. While distribution systems may widely vary in terms of construction material, nearly all transmission pipeline systems are constructed from high-strength steel treated with an anti-corrosive chemical (PHMSA, date unknown).

Pipelines are monitored by system control and data acquisition systems that measure flow rate, temperature and pressure. These systems transfer real-time data via satellite from the pipelines to a control center where valves, pumps, and motors are remotely operated. If tampering with a pipeline 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 285

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occurs, an alarm sounds. The ensuing valve reaction is instantaneous, with the alarm system isolating any rupture and setting off a chain reaction that shuts down pipeline pumps and alerts pipeline operators within seconds.

PIPELINE OVERSIGHT
Pipelines are regulated in California by the Office of the State Fire Marshal Pipeline Safety Division.

CERCLA, the Emergency Planning and Community Right-ta-Know Act, and California law require responsible parties to report hazardous material releases if certain criteria are met. CERCLA requires that all releases of hazardous substances exceeding reportable quantities be reported by the responsible party to the National Response Center. If an accidental chemical release exceeds the Right-to-Know Act applicable minimal reportable quantity, the facility must notify state emergency response commissions and local emergency planning committees for any area likely to be affected by the release, and provide a detailed written follow-up as soon as practicable. Information about accidental chemical releases must be made available to the public.

The California Public Utilities Commission (CPUC) serves as the state regulation authority regarding pipeline operations. The CPUC conducts operation and maintenance compliance inspections and accident investigations. It reviews utilities' reports and records, conducts construction inspections, conducts special studies, and takes action in response to complaints and inquiries from the public on issues regarding gas pipeline safety. The CPUC also endorses the system safety approach embodied in federal government regulations.

The U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA) is responsible for providing federal regulatory oversighL of transmjssion pipelines. The agency's Integrity Management Program is a transmission pipeline program started in 2000. This program focuses on regulations for transmission pipeline in high consequence areas, such as pipelines passing through high population centers or particularly sensitive ecological areas . The Integrity Management Program specifies how pipeline operators must identify, prioritize, assess, repair, and validate the integrity of their pipelines through comprehensive analysis.

PHMSA's 2005 Distribution Integrity Management Program Phase One report found a lack of risk-based assessment in managing distribution pipeline systems. A guidance document was developed to assist operators in deciding what actions are needed to comply with standards of the distribution integrity management program (PHMSA, no date).

In 2002, PHMSA released control guidelines for gas leakage. The guidelines included a regulatory classification for leakage severity, as shown in Table 15-4. 286 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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TABLE 15-4. LEAK CLASSIFICATION
Grade Oescr! tIOn I Exam les Action Criteria
2 3
A leak that represents an
existing or probable hazard
to persons or property and
requires immediate repair or
continuous action until the
conditions are no longer
hazardous.

A leak that is recognized as
being non-hazardous at the
time of detection, but
requires scheduled repair
based on probable future
hazard.

A leak that is non-hazardous
at the time of detection and
can be reasonably expected
to remain non-hazardous.

Because petroleum gas is
heavier than air and will
collect in low areas instead of
dissipating, few leaks can
safely be classified as
Grade 3.

Source: PHMSA, 2002

PIPELINE LOCATIONS
• Any leak which, in the judgment of
operating personnel at the scene is
regarded as an immediate hazard
• Escaping gas that has ignited
• Any indication of gas which has migrated
into or under a building or into a tunnel
• Any reading at the outside wall of a building
or where gas would likely migrate to an
outside wall of a building
• Any leak that can be seen, heard, or felt
and which is in any location that may
endanger the general public or property
Requires prompt action to protect life and
property. Action may require one or more of the
following:
• Implementing a company emergency plan
• Evacuating premises
• Blocking off an area
• Rerouting traffic
• Eliminating sources of ignition
• Venting the area
• Stopping the flow of gas by closing valves or
other means
• Notifying police and fire departments
leaks should be repaired or cleared within one
• Any leak which, under frozen or other calendar year but no later than 15 months from adverse soil conditions, would likely migrate the date they were reported. In determining the to the outside wall of a building (Note: This repair priority, criteria such as the following type of Grade 2 leak must be repaired should be considered:
ahead of seasonal freezelthaw conditions) • Amount and migration of gas • Any leak which, in the judgment of • Proximity of gas to buildings and subsurface operating personnel at the scene, is of elements
sufficient magnitude to justify scheduled • Extent of pavement repair • Soil type and soil conditions such as frost cap, • Any reading under a street in areas without
wall-to-wall paving where it is unlikely the
gas could migrate to the outside wall of a
building
moisture and natural venting
These leaks should be re-evaluated during the
next scheduled survey, or within 15 months of the
date reported, whichever occurs first, until the
leak is re-graded or no longer results in a
reading.

Approximate ly 300,000 miles of gas trans mission pipelines and 170,000 miles of hazar dous liquid pjpelines move their products throughout the United States every day. Transmiss ion pipelines cOJmect urban areas, and only occasionally b'averse highly popu lated areas. Nearly all distribution p ipelines, however, are concentrated in highly populated areas.

Distribution pipelines serve homes and businesses and thus are located where people live and work.

Because of the extensive reach of the distribution system, incidents have the potential to be far reaching.

For examp le, a pipeline leak may release material into a migration pathway , s uch as a sewer line, and reach an ignition source far from the location of the actual leak. Due to the far-reaching underground and u npredi ctable natu re of the p ipeline failur e hazard, it is difficult to gauge the extent to which the hazard affects the Santa Clara County OA. Minor pipe leaks may remain undetected for years until identified during renovation, excavation, or maintenance. In some scenarios, such leaks may go undetected until the severity has increased, resulting in a noticeable smell or, in the worst case scenario, an explosion .
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Utility failure is defined as any interruption or loss of utility service due to disruption of service transmission caused by accident, sabotage, natural hazards, or equipment failure. A significant utility failure is defined as any incident of a long duration, which would require the involvement of the local and/ or state emergency management organizations to coordinate provision of food, water, heating, cooling, and shelter. Widespread outages can occur without warning or as a result of a forecasted event.

Generally, warning times are short in the case of utility failure. In cases where a failure is caused by natural hazards, greater warning time is possible.

Except for the cities of Palo Alto and Santa Clara, Pacific Gas and Electric (PG&E) is responsible for operating and maintaining the electrical transmission and distribution system in the OA. The utility supplies electricity to an approximate population of 1.7 million residential and business customers in 1,260 square miles of the OA. PG&E has both overhead and underground lines throughout the OA. The County of Santa Clara Board of Supervisors recently approved joining the Silicon Valley Clean Energy Authority, creating a local Community Choice Energy Authority that will offer competitive electricity rates and greener electricity sources as early as 2017.

Wastewater and potable water utility restoration are essential to community continuity and recovery .

Interruption of these services may have cascading economic and environmental impacts.

Utility failure can cause secondary hazards:
• Chemical accidents can occur after power is restored to industrial facilities. Power interruptions at chemical handling plants are of particular concern because of the potential for a chemical spill during restart (EPA, 2001).
• Without proper procedures for backup of data and systems, the loss of data, systems, and telecommunications is a risk incurred by utility failure. Data and telecommunications provide a primary method for service to the community by the government and the private sector. A loss of data or a system could result in loss of emergency dispatch capabilities, emergency planning services, infrastructure monitoring capabilities, access to statistical data, and loss of financial and personnel records. Loss of communication capability by first responders could have negative impacts on public safety. Backup systems such as amateur radio operators may be required during disaster to augment communications capabilities. Power outages can also lead to instances of civil disturbance, including looting.

EPIDEMIC AND PANDEMIC
An outbreak or an epidemic exists when there are more cases of a particular disease than expected in a given area, or among a specific group of people, over a particular period of time. In an outbreak or epidemic, it is presumed that the cases are related to one another or that they have a common cause (CDC, 2011).

The Santa Clara County Department of Public Health is responsible to protect and improve the health of the community within the OA. The public health department responds to public health related emergencies and disasters and supports field responders at medical and rescue incidents. The OA has numerous health care facilities within its borders, including the following:
• The Stanford Health Care-Stanford Hospital in Stanford. • El Camino Hospital in Mountain View.
• Santa Clara Medical Center, in Santa Clara.
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• Good Samaritan Hospital in San Jose.
• Kaiser Permanente San Jose Medical Center.
• Lucile Packard Children's Hospital at Stanford.

The following sections describe commonly recognized human health hazards that are a concern in the OA.

Influenza
Epidemics of the flu typically occur in the fall and winter. Because flu seasons fluctuate in length and severity, a single estimate cannot be used to summarize influenza-associated deaths. The U.s. Centers for Disease Control (CDC) estimates that from 2010-2011 to 2013-2014, influenza-associated deaths in the United States ranged from 12,000 (during 2011-2012) to 56,000 (during 2012-2013).

H1Nl
In April 2009, the World Health Organization (WHO) issued a health advisory on an outbreak of influenza-like illness caused by a new subtype of influenza A (AjHlNl) in Mexico and the United States.

The disease spread rapidly, and in June the WHO declared an HINI pandemic, marking the first global pandemic since the 1968 Hong Kong flu. In October, the U.S. declared HINI a national emergency. In August 2010, the WHO declared an end to the pandemic globally. HJNl viruses and seasonal influenza viruses are co-circulating in many parts of the world. It is likely that the 2009 H1N1 virus will continue to spread for years to come, like a regular seasonal influenza virus.

HSN1/H7N9
The highly pathogenic H5Nlavian influenza virus is an influenza A subtype that occurs mainly in birds, causing high mortality among birds and domestic poultry. Outbreaks of highly pathogenic H5Nl among poultry and wild birds are ongoing in a number of countries.

H5N1 virus infections of humans are rare and most cases have been associated with direct poultry contact during poultry outbreaks. Rare cases of limited human-to-human spread of H5Nl virus may have occurred, but there is no evidence of sustained human-to-human transmission. Nonetheless, because all influenza viruses have the ability to change and mutate, scientists are concerned that H5N1 viruses one day could be able to infect humans more easily and spread more easily from one person to another, potentially causing another pandemic.

While the H5N1 virus does not now infect people easily, infection in humans is much more serious when it occurs than is infection with HIN1. More than half of peopLe reported infected with H5Nl have died.

Figure 15-2 summarizes human cases of the virus through 2013.

Infections in humans and poultry by a new avian influenza A virus (H7N9) continue to be reported in China. While mild illness jn human cases has been seen, most patients have had severe respiratory illness and some have died. The only case identified outside of China was recently reported in Malaysia. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 289

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Source: World Health Organization , 2013
FIGURE 15-2. AREAS WITH CONFIRMED HUMAN CASES OF H5N1 2003-2013 Source investigation by Chinese authorities is ongoing. Many of the people infected with H7N9 reportedly have had contact with poultry . However some cases reportedly have not had such contact.

Close contacts of confirmed H7N9 patients are being followed to determine whether any human-to­ human spread of H7N9 is occurring. No sustained person-to-person spread of the H7N9 virus has been found at this time. However, based on previous experience with avian flu viruses, some limited human­ to-human spread of this the virus would not be surprising.

As of the publication of this document, H5N1 and the new H7N9 virus have not been detected in people or birds in the United States.

Smallpox
Smallpox is a sometimes fatal infectious disease. There is no specific treatment, .and the only prevention is vaccination. Symptoms include raised bumps on the face and body of an infected person. The oldest evidence of smallpox was found on the body of Pharaoh Ramses V of Egypt who died in 1157 Be.

Outbreaks have occurred from time to time for thousands of years, but the disease is now eradicated after a successful worldwide vaccination program. The last case of smallpox in the United States was in 1949. The last naturally occurring case in the world was in Somalia in 1977. As of the publication of this document, there are no cases of smallpox in the world. Currently only two locations in the world have samples of smallpox: the CDC in Atlanta and the Ivanovsky Institute of Virology in Russia.

After the disease was eliminated, routine vaccination among the general public was stopped. Therefore, any cases of smallpox in the world would be considered an immediate international emergency. In 2003, 290 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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the Wisconsin Division of Public Health conducted an investigation of state residents who became ill after having contact with prairie dogs. The cases appeared in May and June of 2003, and symptoms in the human cases included fever, cough, pox-like rash and swollen lymph nodes. CDC laboratory test results indicated that the cause of the human illness was Monkeypox, an orthopox virus that could be transmitted by prairie dogs. This outbreak, and the potential use of smallpox as a weapon ofbioterrorism, brought the fear of smallpox back to the forefront of the population. A detailed nationwide smallpox response plan created at the end of 2002 is designed to quickly contain a potential outbreak and vaccinate the population.

Viral Hemorrhagic Fevers
Viral hemorrhagic fevers (VHFs) are a group of illnesses caused by several distinct families of viruses.

VHF describes a multisystem syndrome (multiple systems in the body are affected). Characteristically, the overall vascular system is damaged and the body's ability to regulate itself is impaired . These symptoms are often accompanied by hemorrhage (bleed ing); however, the bJeeding itself is rarely life­ threat enin,g. While some types of hemorrhagic fever viruses can cause relatively mild illnesses, many cause severe, life-threatening disease.

The viruses that cause VHFs are distributed over much of the globe. However, because each virus is associated with one or more particular host species, the virus and the disease it causes are usually seen only where the host species live. Some hosts, such as the rodent species carry ing several of the New World arenaviruses, live in geographically restrict ed areas. Therefore, the risk of g tting VHFs caused by these viruses is restricted to those areas. Other hosts range over continents, such as the rodents that carry viruses that cause the Hantavirus pulmonary syndrome in North and South America, or the rodents that carry viruses that cause hemorrhagic fever with renal syndJ"Ome in Europe and Asia.

Ebola
The 2014 Ebola virus outbreak was unpr ecedented in geogJ'aphical reach and impact on health care syst ms across the globe. This was the largest and deadl iest EboJa virus outbreak ever recorded. It was tile first time the West African countries of Guinea, Liberia, Sierra Leone, Nigeria, Mali, and Senegal saw the virus. Ebola is more common in Central African countries, such as the Democratic Republic of Congo and Sudan, where it was first discovered in 1976. It was also the first time that Ebola made it to the United States and Europe, prompting world-wide preparedness and response efforts. Figure 15-3 shows areas that ultimately were affected. The outbreak was closely. monitored and traveler screenings were developed for those returning from West Africa.

In August 2014 two U.s. healthcare workers return ed to the United States for treatment for Ebola. The case that most impacted the health . care system in the United States was a patient diagnosed with Ebota in Dallas, Texas who died due to Ebola in October 2014. The nurse who provided care for him later tested positive for Ebola. This caused responses across the country from hospitals, emergency medical teams, fire departments and public health agencies to enhance isolation precautions, develop emergency policies, train with personal protective equipment and conduct multi-ag ency emerg ency exercises in case the spread of Ebola became a pandemic.

Before the 2014 outbreak, only 2,200 cases of Ebola had been recorded and 68 percent were fatal. Twenty percent of new Ebola infections were linked to burial traditions in which family and community members wash and touch dead bodies before burial. In Guinea, 60 percent of Ebola infections were linked to traditional burial practices.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 291 Plague

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Plague is a potentially fatal infectious disease of animals and humans caused by the Yersinia pestis bacterium. People usually get plague from being bitten by a flea that is carrying the plague bacterium or by handling an infected animal. Today, modern antibiotics are effective against plague, but if an infected person is not treated promptly, the disease is likely to cause illness or death. • l« .:n,.,,"tp:WtOO r l ":'. 'tot:IrIOUerc.b '''' ~nll) .. l«a »".'Ilpu1oK LU ' Ot.IU," ' Cr tCIaINIU. ..
r::J "I. k¥"'JII._ . ..J ___ 4II . "vlh4~
I I ~'¥~ "'- ~~' t~ ", ,.
("""."t.,.... .... N."' I .... ~u"' ... I .. ..,
_ t'.I"-"'I\· r r "'VlII'.· ''\''J' f'P'"'"· 'Ulll~'''
_ CoII.'),''' U' lJ lI ~ '' . '''.
~U!II'li·fo" l\t ...
.. ·""""'"'"'--1
Source: World Health Organization, 2014
FIGURE 15-3. 2014 DISTRIBUTION OF EBOLA VIRUS OUTBREAKS IN HUMANS AND ANIMALS Plagu e is an ancient disease but outbreaks throughout the world continue. Major plague epidemics occurred in the middle of the sixth century in Egypt, Europe and Asia; during the 14th century in Europe, following caravan routes; in the Wth century in Austria and the Balkans; and in the late 19th century wo.rldwide (but mostly in China and India). Manchuria in 1910-1911 witnessed about 60,000 deaths due to pneumonic plague with a repeat in 1920-1921. A minor outbreak occurred as recently as the summer of 1994 in Surat, India, closely following an earthquake in September 1993. Globally, the WHO reports 1,000 to 3,000 cases of plague every year.

In North America, plague is found in certain animals and their fleas from the Pacific Coast to the Great Plains, and from southwestern Canada to Mexico. The last urban plague epidemic in the United States occurred in Los Angeles in 1924-25. Since then, human plague in the U.S. has occurred as mostly scattered cases in rural areas (an average of 10 to 15 persons each year per the CDC). Most human cases in the United States occur in northern New Mexico, northern Arizona, southern Colorado, California, southern Oregon, and far western Nevada.

Zika Virus
Zika is a disease transmitted by yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus). An Aedes mosquito can only transmit Zika virus after it bites a person who has this virus in their blood. The most common symptoms of Zika are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild, with symptoms lasting for several days to a week after being bitten 292 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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by an infected mosquito. People usually do not get sick enough to go to the hospital, and they rarely die from the Zika virus. For this reason, many people might not realize they have been infected. However, Zika virus infection during pregnancy can cause a serious birth defect called microcephaly (abnormally small head and brain), as well as other severe fetal brain defects. Once a person has been infected, he or she is likely to be protected from future infections. Zika virus is not spread through casual contact, but can be spread by infected men to their sexual partners. There is a growing association between Zika and Guillain-Barre Syndrome, a disease affecting the nervous system.

The mosquitos that carry Zika are not native to California, but infestations have been reported in multiple counties in California. In April 2016, both Santa GaIa and San Mateo counties reported Zika virus cases.

The counties recorded one case each, both linked to individuals who contracted the mosquito-borne virus while traveling outside the United States. Thus far in California, Zika virus infections have been documented only in people who were infected wIllie traveling outside the United States or through sexual contact with an infected traveler. From 2015 to the publishing of this document, there has been no local mosquito-borne transmission of Zika virus in California (Mercury News, April 1, 2016).

Severe Acute Respiratory Syndrome
Severe Acute Respiratory Syndrome (SARS) is a viral respiratory illness caused by a 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 global outbreak was contained. According to the WHO, 8,098 people woddwide became sick with SARS during the 2003 outbreak and 774 died . In the United States, only eight peopl e had laboratory evidence ofSARS­ CoV infection. All of these people had traveled to pal'ts of the world where SARS was present. SARS did not spread more widely in the United States.

In general, SARS begins with a high fever, headache, an overall feeling of discomfort and body aches.

Some people also have mild respiratory symptoms at the outset. About 10 percent to 20 percent of patients have diarrhea, After two to seven days, SARS patients may develop a dry cough. Most patients develop pneumonia.

The main way that SARS seems to spread is by close person-to-person contact. The virus that causes SARS is thought to be transmitted most readily by respiratory droplets produced when an infected person coughs or sneezes. Droplet spread can happen when droplets from the cough or sneeze of an infected person are propelled a short distance (generally up to 3 feet) through the air and deposited on the mucous membranes of the mouth, nose, or eyes of persons nearby . The virus also can spread when a person touches a surface or object contaminated with infectious droplets and then touches his or her mouth, nose, or eyes. It is also possible that the SARS virus might spread more broadly through the air or by other ways that are not now known.

As of May 2005, according to the CDC, there was no remaining sustained SARS transmission anywhere in the world. However, CDC has developed recommendations and guidelines to help pubJic health and healthcare officials plan for and respond quickly to the reappearance of SARS if it occurs again. Lessons learned from the SARS outbreak helped healthcare facilities and communities successfully plan and respond to the 2009 H1N1 pandemic.

FOG
Fog is a cloud near the ground. It forms when air close to the ground can no longer hold all the moisture it contains. This occurs either when air is cooled to its dew point or the amount of moisture in the air increases. Heavy fog is particularly hazardous because it can restrict surface visibility. Severe fog 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 293

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incidents can close roads, cause vehicle accidents, cause airport delays, and impair the effectiveness of emergency response. Financial losses associated with transportation delays caused by fog have not been calculated in. the United States, but it is known to be substantial. Fog can occur almost anywhere during any season and is classified based on how it forms, which is related to where it forms. Certain seasons are more likely to have foggy days or nights based on a number of factors, including topography, nearby bodies of water, and wind conditions.

Fog in the Santa Clara County OA has different origins depending on the time of year. In summer, the area is chru'acterized by cool marine air and persistent coastal stratus and fog. In winter, fog typically originates from the Great Valley. Radiation (ground) fog forms in the .moist regions of the Sacramento River Delta and arriv es to the region via Suisun and San Pablo Bays and San Francisco Bays on cool easterly winds. While this type of fog is less frequent than summer fogs, it is typically denser and more likely to lead to significantly reduced visibility (Golden Gate Weather Services, 2009). Although fog seems like a minor hazard, it can have significant impacts. The California Highway Patrol has records of at least fow' officers whose deaths were indirectly caused by or exacerbated by dense fog and poor visibility (California Highway Patrol, 2016). .

HAZARD PROFILE

PAST EVENTS
State of California

INTENTIONAL HAZARDS
According to the CalOES Terrorism Response Plan, California has had a long history of defending the public against domestic and foreign terrorists. Domestic terrorist groups in California have been focused on political or social issues, while the limited internationally based incidents have targeted the state's immigrant communities due to foreign disputes . Advanced technologies and communication have allowed these groups to become more sophisticated and better organized, with remote members linked electronically. Since 2000, the following terrorist activities have occurred in California:
• On December 2, 2015, 16 people were killed and 22 were seriously injured in an Islamic terrorist attack at the Inland Regional Center in San Bernardino, which consisted of a mass shooting with a semi-automatic pistol and rifle, and an attempted pipe bombing. • On November 4,2015, one person was killed and four were injured as the result of a student stabbing two students and two staff at the University of California, Merced; the attacker was shot and killed by police.
• On November 1, 2013, one person was killed and seven were injured in a shooting attack at Los Angeles International Airport; one TSA officer was killed, two TSA officers and several civilians were injured.
• On February 28, 2008, one person was injured in Los Angeles by animal rights activists attempting a home invasion of a biomedical researcher.
• On November 29, 2005, four people in Santa Cruz were injured from incendiary attacks' by suspected animal rights activists.
• On August 1, 2012, four men in Riverside were arrested for plotting attacks on American military staff and bases overseas (Almendrala, 2012).
• On July 4, 2002, two people were killed and four were injured by an Egyptian gunman at the E1 Al ticket counter at the Los Angeles International Airport (C~N.2003). 294 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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TECHNOLOGICAL HAZARDS
No comprehensive source exists for technological hazard incidents in California. Given the complex system of transportation networks, the large population, and the number of businesses in California, incidents occur on a regular basis throughout the state, as reported by the news media.

EPIDEMIC/PANDEMIC
The most recent data for influenza in the State of California is for the 2014-2015 flu season. The CDPH received 42,812 reports of cases tested positive for influenza. California was impacted by the Enterovirus D68 outbreak in 2014. By October 2014, there were 32 reported cases in the state. Five of those cases were reported in Santa Clara County (Bay City News, 2016). In 2015, California experienced a norovirus outbreak. Between October and December, there were 32 confirmed cases of norovirus (CDPH,2015b).

Regional

INTENTIONAL HAZARDS

TERRORISM INCIDENTS
The South Bay Area has not experienced a major regional terrorism event. Santa Clara County recently hosted the 2016 Super Bowl, which may have increased exposure of the area for potential future terrorist events. Other past events in the region include the following:
• Eco-terrorism - In 2006, three suspected Earth Liberation Front members were arrested in connection with an alleged plot to blow up U.s. Forest Service facilities, cellular phone towers and power-generating stations at various locations in Northern California. The Los Angeles Times reported the FBI and u.s. attorney's office declined to provide details about the alleged evidence against the three, but stated they believe their investigation foiled attacks on a number of sites (Krikorian, 2006).
• Domestic terrorism-On December 3, 1999, the FBI arrested two anti-government militia members who planned a bomb attack at the Suburban Propane facility in Elk Grove, CA. The alleged plot involved a plan to blow up the Suburban Propane site, which stores about 24 million gallons of liquefied propane and is located a mile from residential homes. According to the Sacramento Bee, the plot resulted in heightened on-site security and a year-long investigation resulting in the two arrests.

CVBER INCIDENTS
• In December 2015, the University of California at Berkeley experienced a massive cyber-attack that left upwards of 80,000 people exposed to cyber-crime. The university is one of the largest employers in the Bay Area, and this cyber-attack reached beyond jurisdictional and county lines to affect the entire Bay Area (Bay City News, 2015). • In August 2015, the FBI stated that San Francisco's Bay Area had suffered more than a dozen attacks on its fiber optic infrastructure in the preceding year. The attacks resulted in slow Internet service and disruption of financial transactions and emergency phone calls. The incidents occurred in clusters on single nights around the East Bay and in San Jose, at the heart of Silicon Valley. This led officials to believe the attacks were intentional. Beyond that, officials had yet to find a motive, or any suspects (Fitzgerald, 2015). • On December I, 2014, a global cyber-attack shut down web access to agenda, minutes, and video for many Bay Area government agencies, including Alameda County. The San Francisco-based company Granicus, which provides web services for government agencies nationwide, reported the outage (Johnson, 2014).
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TECHNOLOGICAL INCIDENTS

TRANSPORTATION INCIDENTS

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The Bay Area has not experienced an aircraft accident that caused widespread devastation throughout the region. Aircraft accidents have been localized and somewhat contained.

HAZARDOUS MATERIALS INCIDENTS
The Bay Area has not experienced a hazardous materials release event with a regional affect. Hazardous material releases are often localized due to the limited release of such events.

PIPELINE INCIDENTS
The Bay Area has not experienced a regional pipeline event, but on September 9, 2010, a PG&E 30-inch natural gas line exploded in a neighborhood of San Bruno, approximately 30 miles from the Santa Clara County OA, killing eight people and injuring 58. The fires from the explosion incinerated 38 homes.

UTILITY FAILURE
The Bay Area has not experienced a regional widespread utility failure event, as utility failure is often localized.

Local

INTENTIONAL INCIDENTS

TERRORISM INCIDENTS
In 2014 at PG&E Corporation's Metcalf transmission substation in San Jose, an unknown person entered an underground vault and cut telephone cables. Within half an hour, snipers opened fire on a nearby electrical substation. Shooting for 19 minutes, the persons were able to knock out 17 giant transformers that funnel power to Silicon Valley. Electric-grid officials were able to reroute power around the site and requested power plants in Silicon Valley to produce more electricity, but it took utility workers 27 days to conduct repairs and make the substation functional. The Wall Street Journal reported the incident has been called "the most significant incident of domestic terrorism involving the grid that has ever occurred." There have been no arrests or persons charged for the incident (Smith, 2014).

CVBER INCIDENTS
On April 9, 2009, fiber-optic cable lines belonging to AT&T at two locations were intentionally cut, knocking out phones and access to 911 emergency services to thousands of residential customers and businesses in southern Santa Clara County, in Santa Cruz and San Benito counties and along the Peninsula, (SF Gate, 2009).

TECHNOLOGICAL INCIDENTS

TRANSPORTATION INCIDENTS
The Santa Clara County OA has not experienced a crash of a commercial aircraft or large private plane.

However, a number of general aviation aircraft incidents have occurred at Reid-Hillview Airport and Mineta San Jose International Airport. These incidents are typically localized and contained.

On March 21, 2008, at approximately 7:10 p.m., a southbound two-car light rail train derailed just north of the Virginia station in San Jose. Four people, including the train operator, were injured, and the train was heavily damaged. The East Bay Times reported that, at the time of the accident, trains were operating on a single track through the area because of construction at three nearby light rail stations. The train involved was attempting to switch between tracks when it derailed. Another partial derailment occurred on July 15, 2013, with 12 passengers aboard. CBS San Francisco report there were no deaths or injuries from the accident.
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There have been occasional single vehicle and pedestrian fatality accidents in Santa Clara County.

HAZARDOUS MATERIALS INCIDENTS
Santa Clara county and its incorporated cities have experienced many localized accidental hazardous materials incidents. Four major highways in the OA provide vehicle routes for the transportation of large quantities of hazardous materials : U.S.IOl, 1-880, 1-680, and 1-280. U.S. 101 and 1-880 are the most heavily traveled in terms of truck traffic and are the most frequent location of hazardous materials spills on major roads.

PIPELINE INCIDENTS
According to PHMSA, the OA has experienced the following incidents related to pipeline failure:
• In 2011, PG&E had a natural gas leak due to material weld equipment failure in Santa Clara County.
• In 2012, PG&E had a natural gas leak due to excavation damage to a pipe in Santa Clara County.
• In 2014, PG&E had a natural gas leak due to corrosion of a pipe in Santa Clara County.

Between 2000 and 2016, the County of Santa Clara experienced 339 pipeline incidents with 0 injuries and o fatalities (PHMSA, 2016). In addition, at any given time, pipelines may experience small leaks that are remain unnoticed until discovered by a utilities company or member of the public.

UTILITY FAILURE
The Santa Clara County OA has not experienced an emergency level utility failure, but does regularly experience smaller inconvenient outages.

EPIDEMIC/PANDEMIC
In Santa Clara County, during the 2009 H1N1 influenza pandemic, there were 91 severe cases, 87 intensive care cases, and 21 deaths (CDPH, 2011). Between January I, 2010 and April 4, 2011, 560 confirmed, probable, or suspect cases of pertussis were reported to the Santa Clara County Public Health Department, with 30 hospitalizations and no pertussis-related deaths.

In April 2016, Santa Clara was one of the first counties to report a Zika virus case. Santa Clara and San Mateo recorded one case each, both linked to individuals who contracted the mosquito-borne virus while traveling outside the United States. From 2015 through April 2016 there has been no local mosquito­ borne transmission of Zika virus in California (Mercury News, April 1, 2016).

LOCATION
Intentional Incidents

TERRORISM
The State of California, Office of Homeland Security, and local governments have identified high profile targets for potential terrorists within their jurisdictions. Large business centers, high visibility tourist attractions, transportation providers, and critical infrastructure in Santa Clara County may become a target for terrorism and can present security challenges of an ongoing nature. Multiple incidents can happen simultaneously, and typically require a multi-agency, multi-jurisdictional response (California Department of Toxic Substances Control, 2016).

CYBER THREATS
Municipalities and private businesses within the Santa Clara County OA are susceptible to the most current and common cyber-attacks, such as socially engineered Trojans, unpatched software, phishing attacks, network-traveling worms, and advanced persistent threats. Many of these attacks are engineered 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 297

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to automatically seek technological vulnerabilities. Possible cyberterrorist targets include the banking industry, power plants, air traffic control centers, and water systems.

Technological Incidents

TRANSPORTATION HAZARD
Established truck routes in many jurisdictions in the OA may have a higher potential for hazardous material incidents as a result of traffic accidents. The following transportation corridors and infrastructures have the potential for transportation incidents:
• Interstates 880 (Nimitz Freeway) and 280.
• U.S. Highway 101 and Highway 237.
• State Routes 87, 85, and 17.
• The Mineta San Jose International Airport, which serves approximately 27,000 passengers daily; the airport is served by 12 major airlines, with direct flights to 30 cities and service to more than 180 destinations .
• The Reid-Hillview and South County general aviation airports. • Public transit regional hub facilities in San Jose.
• Three major Bay Area rail lines serving approximately 40,000 riders every weekday from Diridon Station in San Jose: CalTrain; Capitol Corridor (Amtrak); and Altamont Commuter Express.
• Two VIA light rail lines serving 62 stations in the OA over 42 miles. • 73 VIA bus routes in the OA that collectively serve 144,000 average weekday riders. • Feb. 17,2010, a twin-engine Cessna taking off moments earlier from Palo Alto Airport in dense fog struck a PG&E transformer tower, then plummeted toward Beech Street in Palo Alto, shearing off a wing on the roof before bursting into flames. All three of the plane's passengers were killed instantly.

HAZARDOUS MATERIALS
Hazardous materials are stored before and after they are transported to their intended use. This may include service stations that store gasoline and diesel fuel in underground storage tanks; hospitals that store radioactive materials, flammable materials and other hazardous substances; or manufacturers, processors, distributors, and recycling plants for chemical industries that store a variety of chemicals on site (FEMA, 2013). Fixed sites include buildings or property where hazardous materials are manufactured or stored.

The Toxic Substances Control Act of 1976 (TSCA) provides the EPA with authority to require reporting, record-keeping and testing requirements, and restrictions relating to chemical substances and/or mixtures. Certain substances are generally excluded from TSCA, including food, drugs, cosmetics, and pesticides. TSCA addresses the production, importation, use, and disposal of specific chemicals, including polychlorinated biphenyls (PCBs), asbestos, radon, and lead-based paint. No TSCA facilities are identified in the Santa Clara County area.

Hazardous waste information is contained in the Resource Conservation and Recovery Act Information databases (RCRA Info), a national program management and inventory system about hazardous waste handlers. In general, entities that generate, transport, treat, store, and dispose of hazardous waste are required to provide information about their activities to state environmental agencies. These agencies pass on the information to regional and national EPA offices. This regulation is governed by the RCRA, 298 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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as amended by the Hazardous and Solid Waste Amendments of 1984. There are 576 RCRA facilities in the San Jose and Palo Alto areas of the county.

The following are associated with specific risks related to hazardous materials:
• Business and Industrial Areas - Manufacturing, business, and light industrial firms that make semiconductor devices, satellite equipment and systems, computers-electronics manufacturers, semiconductor manufacturing equipment, computer peripherals, government offices, and e-commerce are major employers in the Santa Clara County OA.

These businesses are concentrated in San Jose, Sunnyvale, Cupertino, Santa Clara, Mountain View, and Palo Alto, which could be areas of concern for hazardous materials. Each business is required to file a detailed, confidential plan with the local fire department regarding materials on-site and safety measures taken to protect the public. • Agricultural-Agricultural crops in the OA are primarily nursery crops, mushrooms, bell peppers, spinach and wine grapes. While the use of pesticides is regulated, accidental releases of pesticides, fertilizers, and other agricultural chemicals may be harmful to humans and the environment. Agricultural pesticides are transported daily in and around the Santa Clara County OA en-route to their destination in rural areas of the county. • Illegal Drug Operations-Illegal operations such as laboratories for methamphetamine pose a significant threat. Laboratory residues are often dumped along roadways or left in rented hotel rooms, creating a serious health threat to unsuspecting individuals and to the environment.
• Illegal Dumping - Hazardous wastes such as used motor oil, solvents, or paint are occasionally dumped in remote areas of the Santa Clara County OA or along roadways, creating a potential health threat to unsuspecting individuals and to the environment. • Radioactive Materials - Licensed carriers transport radioactive materials along several transportation routes (Interstate 880 and 280, Highways 101 and 237) through the OA. Cities within the OA are notified in advance of these shipments and commit resources as a standby measure should an accident occur.

PIPELINE HAZARD
Figure 15-4 is a map of gas transmission and hazardous liquid pipelines in the Santa Clara County OA.

The primary operators for the gas transmission pipelines are Chevron Pipeline Company, Kinder Morgan, PG&E, and Wickland Oil Company.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 299 FIGURE 15-4. TRANSMISSION AND HAZARDOUS LIQUID PIPELINES Pipelines in the OA include the following:

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Incidents (Gas)
../' - Gas Transmission Pipelines
-t' - Hazardous Liquid Pipelines
~ • LNG Plants
~ • Breakout Tanks
• Other Populated Areas (scale
dependent)
./. Highly Populated Areas (scale
dependent)
[J State Boundaries
, , . Show Labels
• The San Jose Terminal, owned by Kinder Morgan- A break-out tank in the City of San Jose. • The Bay Area Pipeline, owned by Chevron Pipeline Co. - A 7.85-mile hazardous liquid pipeline used for transporting gasoline, diesel, or jet fuel. • The SJC pipeline, owned by Wickland Oil Company-A 1.98-mile hazardous liquid pipeline that transports jet fuel to the airport.
• The SFPP Concord-San Jose pipeline, owned by Kinder Morgan - A 5.64-mile hazardous liquid pipeline that transport multi-products.
• Nine additional PG&E natural gas lines across the length of the OA.

UTILITY FAILURE
Utility failure or loss of utility service can be caused by accident, sabotage, natural hazards, or equipment failure, although loss of utilities across the entire county are atypical.

Epidemic/Pandemic
The epidemic/ pandemic hazard has not geographic-specific aspect within the Santa Clara County OA.

People throughout the entire OA are susceptible to contagious disease.

Fog
The Pacific, Atlantic Canada, and New England coastlines, along with the valleys and hills in the Appalachian Mountains, are the areas most prone to fog on the North American continent (Keller, 2008).

The Santa Clara County OA, therefore, is more likely to experience fog than many other parts of the country.

The Bay Area, including the Santa Clara County OA, has a unique topography that, when combined with the California climate and nearby bay / maritime resources, creates multiple microclimates.

Microclimates are small but distinct climates within a larger area. Temperature differences of as much as 10°F to 20°F can be found only miles apart in the Bay Area, and those differences can grow significantly 300 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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from one end of the region to another. In spring 2001, Half Moon Bay documented temperatures in the 50s while Antioch in Contra Costa County had temperatures of around 100°F (SF Gate, 2001).

Microclimates are significant in the case of fog, as certain cities in the OA may experience fog while clear skies predominate only a few miles away. Westerly breezes may bring fog from the ocean, but it will be blocked from passing certain points by mountainous ridges. Even the type of fog in microclimates may vary; some regions are more prone to experience radiation fog, while others only receive a canopy of high fog. This is usually based on the proximity of the location to mountains, ridges, fault lines, and water sources, among other factors.

FREQUENCY, EXPOSURE, VULNERABILITY
Frequency, exposure, and vulnerability to the identified hazards of interest and response priorities to such hazards are described in detail in the following plans:
• Santa Clara County Operational Area Emergency Operations Plan and Annexes - The Santa Clara County OA Emergency Operations Plan is an all hazards document describing the OA's Emergency Operations organization, compliance with relevant legal statutes, other guidelines, and critical components of the Emergency Response System. The Emergency Operations Plan consists of threat summaries based on a Santa Clara County OA hazard analysis. This hazard analysis was conducted by Santa Clara County OES staff, providing a description of the local area, risk factors and the anticipated nature of situations that could occur in the Santa Clara County OA. The Emergency Operations Plan is activated during extraordinary emergency situations associated with large-scale disasters affecting the Santa Clara County OA. • Countywide Medical Response System - This Santa Clara County Public Health Department plan outlines the efforts to prepare for response to a disaster that has a medical/health component. The Countywide Medical Response System plan is focused on the goal of terrorism preparedness, and addresses topics such as risk communications, decontamination, personal protective equipment, mass prophylaxis, education, training and exercises. Each topic identifies participating agencies, including fire, law enforcement, hospitals, emergency management, schools, the medical examiner, mental health services, and many others. The plan further enumerates a list of responsibilities to the Countywide Medical Response System for each identified agency, as well as a list of public health commitments through the system that will assist those agencies.
• Hazardous Materials Business Plans - Hazardous materials business plans are implemented by Certified Unified Program Agencies within their jurisdictions, along with local fire departments to protect human health and the environment from hazardous materials incidents.
• Fog-The fog typical for the San Francisco Bay Area is known as advection fog. This type of fog forms when warm, moist and stable air is blown across a cooler surface (land or water).

The air temperature falls until the dew point is reached and condensation occurs. Fog typically occurs in the Bay Area in the June, July and August. It is usually foggy in the morning, with fog burning off as the temperatures rise. There is currently no available data on the number of fog days observed over a time frame for Santa Clara County. However, there are on average 257 sunny days per year in Santa Clara County (www .bestplaces.net / dimate / city/caIifornia / sanj ose).This leaves an average ofl08 days a year when fog may occur within the OA.
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IDENTIFIED NEEDS

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This assessment of the hazards of interest led to identification of the following needs throughout the OA:
• Continue regular and redundant emergency preparedness training for field level responders (police, fire, and public works) and public information staff in order to respond quickly in the event of a disaster associated with the identified hazards of interest. Enhance awareness training for all local government employees to recognize threats or suspicious activity in order to prevent an incident from occurring.
• Continue all facets of hazardous materials team training and response through commitment of resources from the Environmental Health Department, local fire departments, and potential funding through homeland security budgets.
• Continue to improve response times for public safety throughout the OA so as to reduce exposure to human-caused incidents. Maintain appropriate staffing levels of public safety personnel to address vulnerabilities identified in this chapter. • Continue to implement the hazardous materials business plan with enhancements, as warranted by the type of uses in the OA and new technologies in preventing hazardous materials incidents.
• Continue to work proactively with industrial businesses regarding placards and labeling of containers, emergency plans and coordination, standardized response procedures, and notification of the types of materials being transported through the Santa Clara County OA.

On at least an annual basis, conduct random inspections of transporters as allowed by the business; install mitigating techniques at critical locations; implement routine hazard communication initiatives; enhance security along the transportation corridors; and continuously look to the use of safer alternative products to conduct all business and transportation operations.
• Participate in regional, state and federal efforts to gather terrorism information at all levels and keep public safety officials briefed at all times regarding any local threats. Further develop response capabilities based on emerging threats. • Commit support to the Bay Area Urban Area Security Initiative by dedicating fire, emergency medical services, emergency management grant managers, and police personnel to the program as funded with Homeland Security grants.
• Participate in the CalOES Disaster Resistant California annual conference and other training sessions sponsored by regional, state and federal agencies. • Use Crime Prevention Through Environmental Design in future planning efforts as well as enhancing existing infrastructure and buildings to prevent or mitigate human-cause incidents.

Crime Prevention Through Environmental Design is an urban planning design process that integrates crime prevention with neighborhood design and community development. The process is based on the theory that the proper design and effective use of the built environment can reduce crime and the fear of crime and improve the quality of life. It creates an environment where the physical characteristics, building layout, and site planning allow inhabitants to become key agents in ensuring their own security. • Participate in regional training exercises per the requirements of Homeland Security Presidential Directive #8 in support of national preparedness . These training exercises may be sponsored by the u.s. Department of Homeland Security San Jose office, the Bay Area Urban Area Security Initiative, local government offices of homeland security, grant funds 302 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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through CaIOES, or FEMA. Training exercises test and evaluate the ability to coordinate the activities of local and state government first responders, volunteer organizations and the private sector in responding to terrorism and technological hazards. The trainings enhance interagency coordination, provide training to staff, test response and recovery capabilities, and implement the Standardized Emergency Management System, the National Incident Management System, and the California and national mutual aid systems. • Work with the private sector to enhance and create business continuity plans to be followed in the event of an emergency.
• Review existing automatic aid and mutual aid agreements with other public safety agencies to identify opportunities for enhancement.
• Identify, relocate or construct a redundant Emergency Operations Center in a location away from hazards.
• Maintain an emergency services information line that the public can contact 24 hours a day during an emergency to ask questions of emergency staff. • Coordinate with all school districts in the OA and individual cities to ensure that their emergency preparedness plans include preparation for human-caused incidents. • Encourage local businesses to adopt information technology and telecommunications recovery plans.
• Promote 72-hour self-sufficiency through the United Neighborhoods of Santa Clara County and other neighborhood associations, emergency preparedness efforts through local governments, emergency preparedn ess websites of local governm ents, civic organizations and the privat e sector, public outreach , and other means. Ensur e inclusion of program information for people with disabilities and others with access and functional needs. • Prepare and present the human-caused hazard risk and preparedness program to the public through meetings, town hall gatherings, and preparedness fairs and outreach. • Maintain any and all citizen' advisory groups and periodically e-mail emergency preparedness information including human-caused hazard preparedness instructions and reminders .
• Support disease prevention through vaccination and personal emergency and disaster preparation to help reduce the impa cts of human health hazards . • Integrate medical and response personnel in a unified command to prOVide care when needed in response to human health hazards.
• Adequately train and supply medical and response personnel. • Carry out up-to-date and functional all-hazard contingency planning. • Develop a system for informing the public with a unified message about the human health hazard.
• Provide health agencies and facilities with surge capacity management and adaptation to the rising number and needs of the region.
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PART III: MITIGATION STRATEGY
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GOALS AND OBJECTIVES
Hazard mitigation plans must identify goals for reducing long-term vulnerabilities to identified hazards (44 CPR Section 201.6(c)(3)(i». The Core Planning Croup established a guiding principle, a set of goals and measurable objectives for this plan, based on data from the preliminary risk assessment and the results of the public involvement strategy. The guiding principle, goals, objectives and actions in this pla.il all support each other. Goals were selected to support the guiding principle. Objectives were selected that met multiple goals. Actions were prioritized based on the action meeting multiple objectives.

GUIDING PRINCIPLE
A guiding principle focuses the range of objectives and actions to be considered. This is not a goal because it does not describe a hazard mitigation outcome, and it is broader than a hazard-specific objective. The guiding principle for this hazard mitigation plan is as follows:

Carefully plan for the maintenance and enhancement of a disaster-resistant Operational Area by reducing the current and future potential loss of life, property damage, and environmental degradation from various hazards, while accelerating economic recovery from those hazards.

GOALS
The following are the mitigation goals for this plan:

1. Actively develop community awareness, understanding, and interest in hazard mitigation and empower the Operational Area to engage in the shaping of associated mitigation policies and programs.

2. Minimize potential for loss of life, injury, social impacts, and dislocation due to hazards.

3. Minimize potential for damage to property, economic impacts, and unusual public expense due to hazards.

4. Provide essential information to the whole comrtmnity that promotes personal preparedness and includes advice to reduce personal vulnerability to hazards.

5. Encourage programs and projects that promote community resiliency by maintaining the functionality of critical Operational Area resources, facilities, and infrastructure.

6. Promote an adaptive and resilient Operational Area that proactively anticipates the impacts of climate change.

The effectiveness of a mitigation strategy is assessed by determining how well these goals are achieved.

OBJECTIVES
Each selected objective meets multiple goals, serving as a stand-alone measurement of the effectiveness of a mitigation action, rather than as a subset of a goal. The objectives also are used to help establish priorities. The objectives are as follows:

1. Develop and provide updated information about threats, hazards, vulnerabilities, and mitigation strategies to state, regional, and local agencies, as well as private sector groups.

2. Improve understanding of the locations, potential impacts, and linkages among threats, hazards, vulnerability, and measures needed to protect life.

3. Encourage the incorporation of mitigation best management measures into plans, codes, and other regulatory standards for public, private, and non-governmental entities within the Operational Area.
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4. Inform the public on the risk exposure to natural hazards and ways to increase the public's capability to prevent, prepare, respond, recover, and mitigate impacts of these events.

5. Establish and maintain partnerships in the identification and implementation of mitigation measures in the Operational Area.

6. Advance community and natural environment sustainability and resilience to future impacts through preparation and implementation of state, regional, and local projects.

7. Reduce repetitive property losses from all hazards.

8. Where feasible and cost-effective, encourage property protection measures for vulnerable structures located in hazard areas.

9. Improve systems that provide warning and emergency communications. 306 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17 l.

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MITIGATION ALTERNATIVES
Catalogs of natural hazard mitigation alternatives were developed that present a broad range of alternatives to be considered for use in the OA, in compliance with 44 CFR (Section 201.6(c)(3)(ii». One catalog was developed for each natural hazard of concern evaluate d in this plan. The catalogs present alternatives that are categorized in two ways:
• By who would have responsibility for implementation:
.:. Individuals (personal scale) .
• :. Businesses (corporate scale) .
• :. Government (government scale).
• By what the alternative would do:
.:. Manipulate the flooding hazard .
• :. Reduce exposure to the flooding hazard .
• :. Reduce vulnerability to the flooding hazard .
• :. Increase the ability to respond to or be prepared for the flooding hazard.

Hazard mitigation actions recommended in this plan were selected from among the alternatives presented in the catalogs. The catalogs provide a baseline of mitigation alternatives that are backed by a planning process, are consistent with the established goals and objectives, and are within the capabilities of the planning partners to implement. Some of these actions may not be feasible based on the selection criter ia identified for this plan. The purpos e of the catalog was to provide a list of what could be considered to reduce risk of the flood hazard within the OA. Actions in the catalog that are not included for the partnership's action plan were not selected for one or more of the following reasons:
• The action is not feasible.
• The action is already being implemented.
• There is an apparently more cost-effective alternative. • The action does not have public or political support.

The following sections present the catalogs for each hazard are presented in Table 17-1 through Table 17-8.
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TABLE 17-1. ALTERNATIVES TO MITIGATE THE DAM AND LEVEE FAILURE HAZARD Personal-Scale Co orate-Scale Government-Scale
• Manipulate the hazard:
• :. None
• Reduce exposure to the
hazard:
.:. Relocate out of dam
failure inundation
areas.
• Reduce vulnerability to
the hazard:
.:. Elevate home to
appropriate levels.
• Increase the ability to
respond to or be
prepared for the hazard:
.:. Learn about risk
reduction for the dam
failure hazard.
.:. Learn the evacuation
routes for a dam failure
event.
.:. Educate yourself on
early warning systems
and the dissemination
of warnings.
308 I Page
• Manipulate the hazard:
.:. Remove dams.
• :. Remove levees.
.:. Harden dams.
• Reduce exposure to
the hazard:
.:. Replace earthen
dams with hardened
structures.
• Reduce vulnerability to
the hazard:
• :. Flood-proof facilities
within dam failure
inundation areas.
• Increase the ability to
respond to or be
prepared for the
hazard:
.:. Educate employees
on the probable
impacts of a dam
failure.
.:. Develop a continuity
of operations plan.
• Manipulate the hazard:
.:. Remove dams.
.:. Remove levees .
.:. Harden dams .
• Reduce exposure to the hazard:
.:. Replace earthen dams with hardened structures
.:. Relocate critical facilities out of dam failure inundation areas. .:. Consider open space land use in designated dam failure inundation areas.
• Reduce vulnerability to the hazard:
.:. Adopt higher floodplain standards in mapped dam failure inundation areas.
.:. Retrofit critical facilities within dam failure inundation areas . • Increase the ability to respond to or be prepared for the hazard:
.:. Map dam failure inundation areas.
.:. Enhance emergency operations plan to include a dam failure component.
.:. Institute monthly communications checks with dam operators. .:. Inform the public on risk reduction techniques
.:. Adopt rea.I-~state dis~losure requirements for the re-sale of property located Within dam failure inundation areas.
.:. Consider the probable impacts of climate in assessing the risk associated with the dam failure hazard.
.:. Establish early warning capability downstream of listed high hazard dams.
.:. ~onsider the residual risk associated with protection provided by dams In future land use decisions.

Santa Clara County Operational Area Mitigation Plan 10/15/17

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TABLE 17-2. ALTERNATIVES TO MITIGATE THE DROUGHT HAZARD Personal-Scale : Co orate-Sca le Government-Scale
• Manipulate the hazard:
.:. None
• Reduce exposure to the
hazard:
.:. None
• Reduce vulnerability to the
hazard:
.:. Drought-resistant landscapes
.:. Reduce water system losses
.:. Modify plumbing systems
(through water saving kits)
• Increase the ability to respond
to or be prepared for the
hazard:
.:. Practice active water
conservation
10/15/17
• Manipulate the hazard:
.:. None
• Reduce exposure to the
hazard:
.:. None
- Reduce vulnerability to
the hazard:
.:. Drought-resistant
landscapes
.:. Reduce private water
system losses
- Increase the ability to
respond to or be
prepared for the hazard:
.:. Practice active water
conservation
I- Manipulate the hazard:
.:. Groundwater recharge through stormwater management
- Reduce exposure to the hazard:
.:. Identify and create groundwater backup sources
• Reduce vulnerability to the hazard:
.:. Water use conflict regulations
.:. Reduce water system losses
.:. Distribute water saving kits
• Increase the ability to respond to or be prepared for the hazard:
.:. Public education on drought resistance
.:. Identify alternative water supplies for times of drought; mutual aid agreements with alternative suppliers
.:. Develop drought contingency plan
.:. Develop criteria "triggers" for drought-related actions .:. Improve accuracy of water supply forecasts
.:. Modify rate structure to influence active water conservation techniques
Santa Clara County Operational Area Mitigation Plan Page I 309

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T ABLE 17-3. ALTERN ATIVES TO MITIGATE THE E ARTHQUAKE HAZARD Personal-Scale Cor orate-Scale I Government-Scale
• Manipulate the hazard:
.:. None
• Reduce exposure to the hazard:
.:. Locate outside of hazard area (off
soft soils)
• Reduce vulnerability to the hazard:
.:. Retrofit structure (anchor house
structure to foundation)
.:. Secure household items that can
cause injury or damage (such as I
water heaters, bookcases, and
other appliances)
.:. Build to higher design
• Manipulate the hazard:
.:. None
• Reduce exposure to the
hazard:
.:. Locate or relocate mission­
critical functions outside
hazard area where possible
• Reduce vulnerability to the
hazard:
.:. Build redundancy for critical
functions and facilities
.:. Retrofit critical buildings and
areas housing mission­
critical functions
• Increase the ability to respond to or •
be prepared for the hazard:

Increase the ability to
respond to or be prepared for
the hazard: .:. Practice "drop, cover, and hold"
.:. Develop household mitigation plan,
such as creating a retrofit savings
account, communication capability
with outside, 72-hour self­
sufficiency during an event
.:. Keep cash reserves for
reconstruction
.:. Become informed on the hazard
and risk reduction alternatives
available.
.:. Develop a post-disaster action plan
for your household
.:. Adopt higher standard for
new construction; consider
"performance-based design"
when building new structures
.:. Keep cash reserves for
reconstruction
.:. Inform your employees on
the possible impacts of
earthquake and how to deal
with them at your work
facility.
.:. Develop a continuity of
operations plan
• Manipulate the hazard:
.:. None
• Reduce exposure to the hazard:
.:. Locate critical facilities or functions outside hazard area where possible
• Reduce vulnerability to the hazard:
.:. Harden infrastructure
.:. Provide redundancy for critical functions
.:. Adopt higher regulatory standards
• Increase the ability to respond to or be prepared for the hazard:
.:. Provide better hazard maps
.:. Provide technical information and guidance
.:. Enact tools to help manage development in hazard
areas (e.g., tax incentives, information)
.:. Include retrofitting and replacement of critical
system elements in capital improvement plan
.:. Develop strategy to take advantage of post-disaster opportunities
.:. Warehouse critical infrastructure components such
as pipe, power line, and road repair materials
.:. Develop and adopt a continuity of operations plan
.:. Initiate triggers guiding improvements (such as
<50% substantial damage or improvements)
.:. Further enhance seismic risk assessment to target
high hazard buildings for mitigation opportunities.
.:. Develop a post-disaster action plan that includes
grant funding and debris removal components.
310 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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TABLE 17-4. A LTERNATNES TO MITIGATE THE FLOODING HAZARD Personal-Scale : Cor orate-Scale Government-Scale
• Manipulate the
hazard:
.:. Clear storm
drains and
culverts
.:. Use low-impact
development
techniques
• Reduce exposure
to the hazard:
.:. Locate outside of
hazard area
• :. Elevate utilities
above base flood
elevation
.:. Use low-impact
development
techniques
• Reduce
vulnerability to the
hazard:
.:. Raise structures
above base flood
elevation
• :. Elevate items
within house
above base flood
elevation
.:. Build new homes
above base flood
elevation
.:. Flood-proof
structures
• Increase the ability ,
to respond to or be
prepared for the
hazard:
.:. Buy flood
insurance
.:. Develop
household plan,
such as retrofit
savings,
communication
with outside, 72-
hour self­
sufficiency during
and after an
event
I.
• Manipulate the I
hazard: I
• :. Clear storm drains
and culverts
.:. Use low-impact I
development
techniques •
• Reduce exposure to I
the hazard:
.:. Locate critical
facilities or
functions outside
hazard area
.:. Use low-impact .
development
techniques
Manipulate the hazard:
.:. Maintain drainage system
.:. Institute low-impact development techniques on property .:. Dredging, levee construction, and providing regional retention areas .:. Structural flood control, levees, channelization, or revetments . .:. Stormwater management regulations and master planning .:. Acquire vacant land or promote open space uses in developing watersheds to control increases in runoff
Reduce exposure to the hazard:
.:. Locate or relocate critical facilities outside of hazard area .:. Acquire or relocate identified repetitive loss properties .:. Promote open space uses in identified high hazard areas via techniques such as: planned unit developments, easements, setbacks, greenways, sensitive area tracks .
.:. Adopt land development criteria such as planned unit developments, density transfers, clustering
.:. Institute low impact development techniques on property .:. Acquire vacant land or promote open space uses in developing watersheds to control increases in runoff • Reduce
vulnerability to the
hazard:
!. Reduce vulnerability to the hazard:
.:. Build redundancy
for critical
functions or retrofit
critical buildings
.:. Provide flood­
proofing when new
critical
infrastructure must •
be located in
floodplains
• Increase the ability
to respond to or be
prepared for the
hazard:
.:. Keep cash
reserves for
reconstruction
.:. Support and
implement hazard
disclosure for sale
of property in risk
zones.
.:. Solicit cost-sharing
through
partnerships with
others on projects
with multiple
benefits.
.:. Harden infrastructure, bridge replacement program
.:. Provide redundancy for critical functions and infrastructure .:. Adopt regulatory standards such as freeboard standards, cumulative sUbstantial improvement or damage, lower substantial damage threshold; compensatory storage, non-conversion deed restrictions.
.:. Stormwater management regulations and master planning . .:. Adopt "no-adverse impact" floodplain management policies that strive to not increase the flood risk on downstream communities.

Increase the ability to respond to or be prepared for the hazard:
.:. Produce better hazard maps
.:. Provide technical information and guidance
.:. Enact tools to help manage development in hazard areas (stronger controls, tax incentives, and information)
.:. Incorporate retrofitting or replacement of critical system elements in capital improvement plan
.:. Develop strategy to take advantage of post-disaster opportunities .:. Warehouse critical infrastructure components
.:. Develop and adopt a continuity of operations plan
.:. Consider participation in the Community Rating System .:. Maintain and collect data to define risks and vulnerability .:. Train emergency responders
.:. Create an elevation inventory of structures in the floodplain .:. Develop and implement a public information strategy .:. Charge a hazard mitigation fee
.:. Integrate floodplain management policies into other planning mechanisms in OA. .:. Consider the probable impacts of climate change on the risk associated with the flood hazard
.:. Consider the residual risk associated with structural flood control in future land use decisions
.:. Enforce National Flood Insurance Program
.:. Adopt a Stormwater Management Master Plan
TABLE 17-5. ALTERNATNES TO MITIGATE THE LANDSLIDE/MASS MOVEMENT HAZARD 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 311

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Personal-Scale Cor orate-Scale Government-Scale
• Manipulate the hazard:
.:. Stabilize slope (dewater,
armor toe)
.:. Reduce weight on top of slope
.:. Minimize vegetation removal
• Manipulate the hazard:
.:. Stabilize slope (dewater, armor
toe)
.:. Reduce weight on top of slope
and the addition of impervious •
surfaces. Reduce exposure to the hazard:
.:. Locate structures outside of
hazard area (off unstable land
and away from slide-run out
area)
• Reduce exposure to the
hazard:
.:. Locate structures outside of
hazard area (off unstable land
and away from slide-run out
area)
• Reduce vulnerability to the
hazard:
.:. Retrofit home
• Increase the ability to respond
to or be prepared for the
hazard:
.:. Institute warning system, and
develop evacuation plan
.:. Keep cash reserves for
reconstruction
.:. Educate yourself on risk
reduction techniques for
landslide hazards
• Reduce vulnerability to the
hazard:
• :. Retrofit at-risk facilities
• Increase the ability to respond
to or be prepared for the hazard:
.:. Institute warning system, and
develop evacuation plan
.:. Keep cash reserves for
reconstruction
.:. Develop a continuity of
operations plan
.:. Educate employees on the
potential exposure to landslide
hazards and emergency
response protocol.
• Manipulate the hazard:
.:. Stabilize slope (dewater, armor toe)
.:. Reduce weight on top of slope
• Reduce exposure to the hazard:
.:. Acquire properties in high-risk landslide areas.
.:. Adopt land use policies that prohibit the placement of habitable structures in high-risk landslide areas.
• Reduce vulnerability to the hazard:
.:. Adopt higher regulatory standards for new
development within unstable slope areas.
.:. Armor/retrofit critical infrastructure against the impact of landslides .
• Increase the ability to respond to or be prepared for the hazard:
.:. Produce better hazard maps
.:. Provide technical information and guidance
.:. Enact tools to help manage development in hazard
areas: better land controls, tax incentives, information .:. Develop strategy to take advantage of post-disaster opportunities
.:. Warehouse critical infrastructure components
.:. Develop and adopt a continuity of operations plan
.:. Educate the public on the landslide hazard and
appropriate risk reduction alternatives.
312 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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TABLE 17-6. ALTERNATIVES TO MITIGATE THE SEVERE WEATHER HAZARD Personal-Scale Cor orate-Scale Government-Scale
• Manipulate the hazard:
-:- None
• Reduce exposure to the hazard:
-:- None
• Reduce vulnerability to the hazard:
-:- Insulate house
-:- Provide redundant heat and power
-:- Insulate structure
-:- Plant appropriate trees near home
and power lines ("Right tree, right
place" National Arbor Day
Foundation Program)
• Increase the ability to respond to
or be prepared for the hazard:
-:- Trim or remove trees that could
affect power lines
-:- Promote 72-hour self-sufficiency
-:- Obtain a NOAA weather radio.
-:- Obtain an emergency generator.
• Manipulate the hazard:
-:. None
• Reduce exposure to the
hazard:
-:. None
• Reduce vulnerability to the
hazard:
-:- Relocate critical
infrastructure (such as power
lines) underground
-:- Reinforce or relocate critical
infrastructure such as power
lines to meet performance
expectations
.:- Install tree wire
• Increase the ability to
respond to or be prepared for
the hazard:
-:- Trim or remove trees that
could affect power lines
-:- Create redundancy
.:- Equip facilities with a NOAA
weather radio
.:. Equip vital facilities with
emergency power sources.
,• Manipulate the hazard:
.:- None
• Reduce exposure to the hazard:
-:- None
• Reduce vulnerability to the hazard:
-:- Harden infrastructure such as locating utilities
underground
-:- Trim trees back from power lines
• Increase the ability to respond to or be prepared for the hazard:
-:- Support programs such as ''Tree Watch" that
proactively manage problem areas through use of
selective removal of hazardous trees, tree
replacement, etc.
-:- Increase communication alternatives
-:. Modify land use and environmental regulations to
support vegetation management activities that
improve reliability in utility corridors.
.:- Modify landscape and other ordinances to
encourage appropriate planting near overhead
power, cable, and phone lines
-:- Provide NOAA weather radios to the public
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 313

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TABLE 17-7. A LTERNATIVES TO MITIGA TE THE TSUNAMI HAZARD • Manipulate the hazard:
.:. None
• Reduce exposure to the
hazard:
.:. Locate outside of hazard
area
• Reduce vulnerability to the
hazard:
.:. Apply personal property
mitigation techniques to
your home such as
anchoring your foundation
and foundation openings to
allow flow through
• Increase the ability to
respond to or be prepared
for the hazard:
• :. Develop and practice a
household evacuation plan.
.:. Support/participate in the
Redwood Coast Tsunami
Working Group.
.:. Educate yourself on the risk
exposure from the tsunami
hazard and ways to
minimize that risk.
314 I Page
• Manipulate the hazard:
.:. None
'. Manipulate the hazard:

I .:. Build wave abatement structures (e.g. the "Jacks" looking structure designed by the Japanese)
I-
• Reduce exposure to the I
hazard:
• :. Locate structure or mission
critical functions outside of
hazard area whenever
possible
Reduce exposure to the hazard:
.:. Locate structure or functions outside of hazard area whenever possible .
.:. Harden infrastructure for tsunami impacts.
• Reduce vulnerability to the
hazard:
.:. Mitigate personal property
for the impacts of tsunami
• Increase the ability to
respond to or be prepared
for the hazard:
.:. Develop and practice a
corporate evacuation plan.
.:. Support/participate in the
Redwood Coast Tsunami
Working Group.
• :. Educate employees on the
risk exposure from the
tsunami hazard and ways to
minimize that risk
.:. Relocate identified critical facilities located in tsunami high hazard areas.
• Reduce vulnerability to the hazard:
.:. Adopt higher regulatory standards that will provide higher. levels of protection to structures built in a tsunami inundation area.
.:. Utilize tsunami mapping once available, to guide
development away from high risk areas through land use
planning
• Increase the ability to respond to or be prepared for the hazard:
.:. Create a probabilistic tsunami map for the OA .
.:. Provide incentives to guide development away from hazard areas.
.:. Develop a tsunami waming and response system .
.:. Provide residents with tsunami inundation maps
.:. Join NOAAis Tsunami Ready program
.:. Develop and communicate evacuation rou t~s .
.:. Enhance the public information program to Include nsk reduction options for the tsunami hazard
Santa Clara County Operational Area Mitigation Plan 10/15/17

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TABLE 17-8. AL TERN A TIVES TO MITIGATE THE WILDFIRE HAZARD 1- cale Co orate-Scale Government-Scale
• Manipulate the hazard:
.:. Clear potential fuels on property
such as dry overgrown
underbrush and diseased trees
• Reduce exposure to the hazard:
.:. Create and maintain defensible
space around structures
.:. Locate outside of hazard area
.:. Mow regularly
• Reduce vulnerability to the
hazard:
.:. Create and maintain defensible
space around structures and
provide water on site
.:. Use fire-retardant building
materials
.:. Create defensible spaces
around home
• Increase the ability to respond
to or be prepared for the hazard:
.:. Employ techniques from the
National Fire Protection
Association's Firewise
Communities program to
safeguard home
.:. Identify alternative water
supplies for fire fighting
.:. Install/replace roofing material
with non-combustible roofing
materials.
10/15/17
• Manipulate the hazard:
.:. Clear potential fuels on
property such as dry
underbrush and
diseased trees
• Reduce exposure to the
hazard:
.:. Create and maintain
defensible space around
• Manipulate the hazard:
.:. Clear potential fuels on property such as dry underbrush and diseased trees
.:. Implement best management practices on public lands. • Reduce exposure to the hazard:
.:. Create and maintain defensible space around structures and infrastructure
.:. Locate outside of hazard area
.:. Enhance building code to include use of fire resistant materials in high hazard area.
structures and • Reduce vulnerability to the hazard: infrastructure I .:. Locate outside of hazard .:. Create and maintain defensible space around structures and infrastructure area
• Reduce vulnerability to
the hazard:
.:. Create and maintain
defensible space around
structures and
infrastructure and
provide water on site
.:. Use fire-retardant
building materials
.:. Use fire-resistant
plantings in buffer areas
of high wildfire threat.
• Increase the ability to
respond to or be
prepared for the hazard:
.:. Support Firewise
community initiatives.
• :. Create /establish stored
water supplies to be
utilized for firefighting.
.:. Use fire-retardant building materials
.:. Use fire-resistant plantings in buffer areas of high wildfire threat.
.:. Consider higher regulatory standards (such as Class A roofing)
.:. Establish biomass reclamation initiatives
I. Increase the ability to respond to or be prepared for the hazard:
.:. More public outreach and education efforts, including an active Firewise program
.:. Possible weapons of mass destruction funds available to enhance fire capability in high-risk areas
.:. Identify fire response and alternative evacuation routes .:. Seek alternative water supplies
.:. Become a Firewise community
.:. Use academia to study impacts/solutions to wildfire risk .:. Establish/maintain mutual aid agreements between fire service agencies.
.:. Create/implement fire plans .
.:. Consider the probable impacts of climate change on the rtsk associated with the wildfire hazard in future land use
decisions
Santa Clara County Operational Area Mitigation Plan Page I 315

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AREA-WIDE ACTION PLAN AND IMPLEMENTATION
The Working Group reviewed the catalogs of haza.rd mitigation alternativ es and selected a.rea-wide actions to be induded in a hazard mitigation action plan. The selection of area-wide actions was based on the risk assessment of identified haza.rds of concern and the defined hazard mitigation goals and objectives. Table IS-1 lists the recommended hazard mitigation actions that make up the action plan . The timeframe indicated in the table is defined as follows:
• Short Term = to be completed in 1 to 5 years.
• Long Term = to be completed in greater than 5 years.
• Ongoing = currently being funded and implemented under existing programs .

TABLE 18-1. SANTA CLARA COUNTY OPERATIONAL AREA ACTION PLAN Hazards Addressed : Ob·ectives Met I Lead A enc Fundln 0 lions Tlmeframe Action SCOA·1-Continue to maintain a website that will house the operational-area hazard mitigation plan, its progress reports, and all components of the plan's maintenance strategy to provide the planning partners and public ongoing access to the plan and its implementation.

All 1,2,3,4,5,6,9 Santa Clara County Santa Clara County OES 0 . . ngo'"g OES Operating Budget Action SCOA·2-Continue to leverage, support and enhance ongoing, regional public education and awareness programs as a method to educate the public on risk, risk reduction and community resilience.

All 1, 2,4,9
Santa Clara County
OES and all planning I Local
partners
Ongoing
Action SCOA·3-Continue ongoing communication and coordination in the implementation of the Santa Clara County Operational Area Hazard Mitigation Plan.

All 1,2,3,4,5,6,7,8,9
Santa Clara County
OES and all planning Local
partners
Ongoing
Action SCOA·4-Continue to support the use, development and enhancement of a regional crisis communications system Santa Clara County Local, possible grant
All 1, 4, 5, 9 OES and all planning funding (FEMA, DHS, Ongoing partners NWS, NOAA)
Action SCOA·5-Strive to capture time-sensitive, perishable data-such as high water marks, extent and location of hazard, and loss information-following hazard events to support future updates to the risk assessment.

Santa Clara County
All 2, 3, 6 OES and all planning Local, FEMA (PA) Short-term partners
Action SCOA·6-ldentify new and comprehensive hazard datasets to improve and augment future updates to the risk assessment Santa Clara County
All 2, 3, 5, 6, 7, 8 OES and all planning Local Ongoing partners

BENEFIT-COST REVIEW
The action pJan must be prioritized according to a benefit/cost analysis of the proposed projects and their associated costs (44 CFR, Section 201.6(c)(3)(iil». The benefjts of proposed projects were weighed against estimated costs as part of the project prioritization process . The benefit/ cost analysis was not of the detailed variety required by FEMA for project grant eligibility under Hazard Mitigation Assistance 316 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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grants. A less formal approach was used because some projects may not be implemented for up to 10 years, and associated costs and benefits could change dramatically in that time. Therefore, a review of the apparent benefits versus the apparent cost of each project was performed. Parameters were established for assigning subjective ratings (high, medium, and low) to the costs and benefits of these projects.

Cost ratings were defined as follows:
• High - Existing funding will not cover the cost of the project; implementation would require new revenue through an alternative source (for ~xample, bonds, grants, and fee increases). • Medium - The project could be implemented with existing funding but would require a re­ apportionment of the budget or a budget amendment, or the cost of the project would have to be spread over multiple years.
• Low - The project could be funded under the existing budget. The project is part of or can be part of an ongoing existing program.

Benefit ratings were defined as follows:
• High - Project will provide an immediate reduction of risk exposure for life and property. • Medium - Project will have a long-term impact on the reduction of risk exposure for life and property, or project will provide an immediate reduction in the risk exposure for property. • Low - Long-term benefits of the project are difficult to quantify in the short term.

Using this approach, projects with positive benefit versus cost ratios (such as high over high, high over medium, medium over low, etc.) are considered cost-beneficial and are prioritized accordingly.

For many of the strategies identified in this action plan, financial assistance may be available through Hazard Mitigation Assistance grants, aU of which require detailed benefit/ cost analyses. These analyses will be performed on projects at the time of application using the FEMA benefit-cost model. For projects not seeking financial assistance from grant programs that require detailed ana lysis, "benefits" can be defined according to parameters that meet the goals and objectives of this plan.

AREA-WIDE ACTION PLAN PRIORITIZATION
Table 18-2 lists the priority of each area-wide action.

TABLE 18-2. PRIORITIZATION OF OPERATIONAL AREA-WIDE MITIGATION ACTIONS # of Do Benefits ,Is project Can Project be Funded Pnonty Action # Objectives Benefits Costs Equal or I Grant under EXlstrng (High . Med ., Met Exceed Costs? ~ Eli Ible? Pro rams! Bud ets? Low
SCOA-1 7 Medium Low Yes No Yes High
SCOA-2 4 High Medium Yes Yes Yes High
SCOA-3 9 High Medium Yes Yes Yes High
SCOA-4 4 Medium Medium Yes Yes Yes High
SCOA-5 3 Medium Medium Yes Yes No High
SCOA-6 6 Hi~h Medium Yes Yes Yes Hi9h
A qualitative benefit-cost review was performed for each of these actions. The priorities are defined as follows:
• High Priority-A project that meets multiple objectives (i.e., multiple hazards), has benefits that exceed cost, has funding secured or is an ongoing project and meets eligibility 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 317

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requirements for Hazard Mitigation Assistance grants. High priority projects can be completed in the short term (1 to 5 years).
• Medium Priority - A project that meets goals and objectives, that has benefits that exceed costs, and for which funding has not been secured but that is grant eligible under Hazard Mitigation Assistance grants or other grant programs. Project can be completed in the short term, once funding is secured. Medium priority projects will become high priority projects once funding is secured.
• Low Priority - A project that will mitigate the risk of a hazard, that has benefits that do not exceed the costs or are difficult to quantify, for which funding has not been secured, that is not eligible for Hazard Mitigation Assistance grant funding, and for which the time line for completion is ]ong term (1 to 10 years). Low priority projects may be eligible for other sources of grant funding from other programs.

ANALYSIS OF AREA-WIDE MITIGATION ACTIONS
Each recommended action was classified based on the hazard it addresses and the type of mitigation it involves. Table 18-3 shows the classification based on this analysis.

TABLE 18-3. ANALYSIS OF MITIGATION ACTIONS
I ~ction_~ lJJ~t A<!9ress th_e Hazar~-,_by f\IIItlgallon IYr?e_ . ____ _ _ _ _ _ __ __ Hazard Event P t Propert y Ed t d R Emergency I Structural Climate I I PubliC Natural I I reven Ion uca Ion an esource Protection APt t I' Servlces I Projects ReSilient wareness ro ec Ion Dam/Levee Failure SCOA-3, SCOA-5 SCOA-1, SCOA-2, SCOA-6 SCOA-4, SCOA-2, SCOA-6 SCOA-3, SCOA-4 SCOA-6 SCOA-5
Drought SCOA-3 SCOA-5 SCOA-1, SCOA-2, SCOA-6 SCOA-4, SCOA-2 SCOA-3, SCOA-4 SCOA-6 Earthquake SCOA-3 SCOA-5 ! SCOA-1, SCOA-2, SCOA-6 SCOA-4, SCOA-2 i SCOA-3, SCOA-4 SCOA-6 Flooding SCOA-3, SCOA-5 SCOA-1, SCOA-2, SCOA-6 SCOA-4, SCOA-2, SCOA-5 SCOA-3, SCOA-4 SCOA-6 SCOA-5
Landslide/Mass SCOA-3 SCOA-5 SCOA-1, SCOA-2, SCOA-6 SCOA-4, SCOA-2, Movement SCOA-3, SCOA-4 SCOA-6 SCOA-5
Severe Weather SCOA-3 SCOA-5 SCOA-1, SCOA-2, SCOA-6 SCOA-4, SCOA-2 SCOA-3, SCOA-4 SCOA-6 Wildfire SCOA-3 SCOA-5 SCOA-1, SCOA-2, SCOA-6 iSCOA-4, SCOA-2, SCOA-3, SCOA-4 ISCOA-6 SCOA-5
Mitigation types used for this ca~egorization are as follows:
• Prevention-Government, administrative or regulatory actions that influence the way land and buildings are developed to reduce hazard losses. Includes planning and zoning, floodplain laws, capital improvement programs, open space preservation, and storm water management regulations.
• Property Protection - Modification of buildings or structures to protect them from a hazard or removal of structures from a hazard area. Includes acquisition, elevation, relocation, structural retrofit, storm shutters, and shatter-resistant glass. • Public Education and Awareness-Actions to inform citizens and elected officials about hazards and ways to mitigate them. Includes outreach projects, real estate disclosure, hazard information centers, and school-age and adult education. 318 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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• Natural Resource Protection-Actions that minimize hazard loss and preserve or restore the functions of natural systems. Includes sediment and erosion control, stream corridor restoration, watershed management, forest and vegetation management, and wetland restoration and preservation.
• Emergency Services - Actions that protect people and property during and immediately after a hazard event. Includes warning systems, emergency response services, and the protection of essential facilities.
• Structural Projects - Actions that involve the construction of structures to reduce the impact of a hazard. Includes dams, setback levees, floodwalls, retaining walls, and safe rooms. • Climate Resilient- Actions that minimize the impacts of climate change via an aquifer storage and recovery system to increase water supply for drought mitigation and a flood diversion and storage project to reduce flood risk.

PLAN ADOPTION
A hazard mitigation plan must document that it has been formally adopted by the governing bodies of the jurisdictions requesting federal approval of the plan (44 CFR Section 201.6(c)(5». For multi­ jurisdictional plans, each jurisdiction requesting approval must document that is has been formally adopted . This plan will be submitted for a pre-adoption review to CaIOES and FEMA Region IX prior to adoption. Once pre-adoption approval has been provided, all planning partners will formally adopt the plan. DMA compliance and its benefits cannot be achieved until the plan is ado pted. Copies of the resolutions adopting this plan for all planning partners can be found in Appendix C of this volume .

PLAN MAINTENANCE STRATEGY
A hazard mitigation plan must present a plan maintenance process that includes the following (44 CFR Section 201.6(c)(4»:
• A section describing the method and schedule of monitoring, evaluating, and updating the mitigation plan over a 5-year cycle.
• A process by which local governments incorporate the requirements of the mitigation plan into other planning mechanisms, such as comprehensive or capital improvement plans, when appropriate.
• A discussion on how the community will continue public participation in the plan maintenance process.

This section details the formal process that will ensure that the Hazard Mitigation Plan remains an active and relevant document and that the planning partners maintain their eligibility for applicable funding sources. The plan maintenance process includes a schedule for monitoring and evaluating the plan annually and producing an updated plan every five years. This chapter also 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, capital improv ement 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.

Pursuant to 44CFR 201.6(c)(4)(i), the plan maintenance matrix shown in Table 18-4 provides a synopsis of responsibilities for plan monitoring, evaluation, and update, which are discussed in further detail in the sections below .
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 319 TABLE 18-4. PLAN MAINTENANCE MATRIX

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I Support
Task IA roach Tlmel lne I Lead Res onslbili t Responsibilit Preparation of status updates and January to February or Monitoring action implementation tracking as part upon comprehensive of submission for Annual Progress update to General Plan or R~port. major disaster
! Review the status of previous actions
: as submitted by the monitoring task
Evaluation ! lead and support to assess the
i effectiveness of the plan; compile and
finalize the An~ual ~rogress Report
. Reconvene the planning partners, at
i a minimum, every 5 years to guide a
Update • comprehensive update to review and
revise the plan.

PLAN IMPLEMENTATION
Finalized progress report
completed by March 1 of
each year
Every 5 years or upon
comprehensive update to
General Plan or major
disaster
Jurisdictional points of
contact identified in
. Volume 2 annexes
Jurisdictional
implementation lead
identified in Volume 2
. annexes
Core Planning Group (via Jurisdictional points of
Santa Clara County OES); contacts identified in
Plan Maintenance element Volume 2 annexes
Core Planning Group (via Jurisdictional points of
Santa Clara County OES); contacts identified in
Plan Maintenance element Volume 2 annexes
. The effectiveness of the hazard mitigation plan depends on its implementation and incorporation of its action items into existing local plans, policies and programs. Together, the action items in the Plan provide a framework for activities that the planning partners Can implement over the next 5 years. The Working Group has established goals and objectives and have prioritized mitigation actions that will be implemented through existing plans, policies, and programs.

The Core Planning Group, in coordination with the WOlking Group, will have lead responsibility for overseeing the overall plan im.plementation and maintenance strategy. Plan implementation and evaluation will be a shared responsibility among al1 planning partners and agencies identified as lead agencies in the mitigation action plans and according to local governing protocols (see planning partner annexes in Volume 2 of this plan).

PLAN MAINTENANCE ELEMENT
The Working Group is a total volunteer body that oversaw th.e development of the Plan and made reconunendations on key elements of the plan, including the maintenance strategy . It was the Working Group's position that an overSight committee with representation simil.ar to that of the Working Group should have an active role in the plan maintenance strategy. Therefore, it is recommended that a Plan Maintenance element remain a viable body involved in key elements of the plan maintenance strategy.

T.he Plan Maintenance element should include representation from all planning partners and other stakeholders in the OA.

The principal role of the Plan Maintenance element will be to review the annual progress report and provide input to the Core Planning Group (via Santa Clara County OES) and the Emergency Operational Area Council (EOAC) on possible enhancements to be considered at the next update. Future plan updates may be overseen by a new working group, similar to the one that participated in this update. Keeping an interim Plan Maintenance element intact will therefore provide a head start on future updates. Data compilation for the progress report is the responsibHity of each planning partner, not the responsibility of the Plan Maintenance element. The Plan Maintenance element's role will simply be to review the progress report in order to identify issues needing to be addressed by future plan updates. 320 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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ANNUAL PROGRESS REPORT REQUIREMENT
The minimum task of each planning partner will be the evaluation of the progress of its individual action plan during a 12-month performance period. This review will include the following:
• Summary of any hazard events that occurred during the performance period and the impact these events had on the OA.
• Review of mitigation success stories.
• Review of continuing public involvement.
• Brief discussion about why targeted strategies were not completed. • Re-evaluation of the action plan to determine if the timeline for identified projects needs to be amended (such as changing a long-term project to a short-term one because of new funding).
• Recommendations for new projects.
• Changes in or potential for new funding options (grant opportunities). • Impact of any other planning programs or actions that involve hazard mitigation.

The Core Planning Group has created a streamlined approach for preparing a progress report. A template for future progress reports is provided in Appendix B of this volume. The Plan Maintenance element will provide feedback to the Core Planning Group on items included in the template. The Core Planning Group will then prepare a formal annual report on the progress of the plan. This report should be used as follows:
• Posted on the Santa Clara County OES website page dedicated to the hazard mitigation plan. • Provided to the local media through a press release.
• Presented to planning partner governing bodies to inform them of the progress of actions implemented during the reporting period.
• Conducted between January and February of each year to position the Operational Area for Pre-Disaster Mitigation funding opportunities beginning March 1.

Annual progress reporting is not a requirement specified under 44 CFR, but is a requirement for credit under the CRS program activity 510. However, it may enhance the planning partners' opportunities Jor funding. While failure to implement this component of the plan maintenance strategy will not jeopardize a planning partner's compliance under the OM A, it may jeopardize its opportunity to partner and leverage funding opportunities with the other partners. Each planning partner was informed of these protocols at the beginning of this planning process (in the "Planning Partner Expectations" package provided at the start of the process), and each partner acknowledged these expectations with submittal of a letter of intent to participate in this process.

TWICE-YEARLY PROGRESS REPORT OPTION
During the planning process, the Core Planning Group and Working Group identified an added benefit for twice-yearly progress reporting during the plan performance period . Twice-yearly progress reporting, while not mandated as part of this plan maintenance procedure, can provided added benefit in the following areas:
• Community Rating System (CRS) recertification preparation for CRS communities. • Streamlined coordination and assessment to pursue grant funds following a disaster declaration.
• Continuity of knowledge to prevent plan maintenance lapse due to staff turnover. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 321

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Community Rating System
Twice-yearly progress reporting will serve a primary benefit to communities participating in CRS. As part of annual recertification for the CRS program with no formal audit, CRS communities are required to report on the status of their mitigation initiatives. These re-certifications occur on October 1 of each year, approximately six months after the annual progress reporting period that will be led by the Core Planning Group. As such, twice-yearly reporting is recommended to capture any additional progress achieved since the annual progress report development. To meet this recertification timeline, the CRS communities should strive to complete twice-yearly progress reports between August and September each year.

It is understood by the CRS participating communities within the OA that a formal progress report is to be submitted with its annual recertification once a community receives credit for planning under CRS activity 510. If there has been no change in status of any action during the period for the initial progress reporting and the due date for the CRS annual recertification (October I), then submittal of the initial report will suffice for CRS progress reporting requirements. However, a community can receive additional credit points under CRS activity 510 for fully committing to twice-yearly progress reporting.

Post-Disaster Funding
Once a major disaster occurs in the OA, Hazard Mitigation Grant Program funds may become available on a competitive basis. Planning partners may choose to update their progress on their selected strategies for the purpose of identifying appropriate projects for which to pursue HMGP funds. Additionally, planning partners may identify appropriate multi-jurisdictional initiatives specific to the hazard and damage experienced, in order to tailor their grant submissions for maximum benefit. The occurrence of a presidentially declared disaster in the OA that triggers grant funding may also trigger a formal update to this hazard mitigation plan, as described below.

Staff Turnover
During any given year, staff turnover may disrupt normal operations of participation planning partners.

If key points of contact leave, knowledge for action plan progress or standard practices may be lost. By conducting a twice-yearly progress report prior to a major staff change, jurisdictions provide a road map for knowledge transfer between outgoing and incoming staff.

Twice-Yearly Progress Reporting Assistance
Santa Clara County OES will provide assistance to jurisdictions seeking to conduct a progress report outside of the annual progress reporting period. This assistance may include providing a copy of the most recently completed annual progress report and guidance on how to review and report on the mitigation action list, recommendations on prioritization.

PLAN UPDATE
Local hazard mitigation plans must be reviewed, revised if appropriate, and resubmitted for approval in order to remain eligible for benefits under the DMA (44 CFR, Section 201.6(d)(3)). The planning partners intend to update the hazard mitigation plan on a 5-year cycle from the date of initial plan adoption. This cycle may be accelerated to less than 5 years based on the following triggers:
• A Presidential Disaster Declaration that impacts the OA. • A hazard event that causes loss of life.
• A comprehensive update of a planning partner's general plan. 322 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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It will not be the intent of future updates to develop a complete new hazard mitigation plan for the OA.

The update will, at a minimum, include the following elements:
• The update process will be convened through a new Working Group . • The hazard risk assessment will be reviewed and, if necessary, updated using best available information and technologies.
• The action plans will be reviewed and revised to account for any actions completed, dropped, or changed and to account for changes in the risk assessment or new policies identified under other planning mechanisms (such as the general plan) .
• The draft update will be sent to appropriate agencies and organizations for comment. • The public will be given an opportunity to comment on the update prior to adoption. • Planning partner governing bodies will adopt the updated plan.

GRANT MONITORING AND COORDINATION
The Working Group recognized the importance of having an annual coordination period that helps each planning partner become aware of upcoming mitigation grant opportunities identifies multi-jurisdiction projects to pursue. Grant monitoring will be the responsibility of the Core Planning Group (via Santa Clara County OES) as part of the annual progress report coordination responsibilities. Santa Clara County OES will keep the planning partners apprised of Hazard Mitigation Assistance grant openings and provide technical guidance and expertise in developing the HMA sub-applicant package . In cases where jurisdictions wish to pursue funding for multi-jurisdiction initiatives, Santa Clara County OES will provide each participating jurisdiction with the guidance needed to complete a joint sub-applicant package.

Santa Clara County OES intends to be a resource to the planning partnership in the support of project grant writing and development. The degree of this support will depend on the level of assistance requested by the partnership during open windows for grant applications. It is not Santa Clara County OES's intent to lead any grant application effort for any specific planning partner requesting assistance.

It will be the role of Santa Clara County OES staff to provide support to a lead jurisdiction by providing or identifying resources for project development, scoping, feasibility, grant writing, environmental/historic preservation application, and benefit! cost analyses . As part of grant monitoring and coordination, Santa Clara County OES agrees to provide the following :
• Notification to planning partners about impending grant opportunities. • A current list of eligible, jurisdiction-specific projects for funding pursuit consideration . • Notification about mitigation priorities for the fiscal year to assist the planning partners in the selection of appropriate projects.
• Training on the FEMA benefit-cost analysis tool upon request. • Training on the sub-applicant system (eGrants) upon request. • Grant writing technical assistance upon request.
• Technical review of the completed sub-applicant package upon request.

Grant monitoring and coordination is expected to occur on an annual basis in coordination with the annual progress report or as needed based on the availability of non-HMA or post-disaster funding opportunities.
10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 323

CONTINUING PUBLIC INVOLVEMENT

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The public will continue to be apprised of the plan's progress through the Santa Clara County OES website and by providing copies of annual progress reports to the media . Each planning partner has agreed to provide links to the hazard mitigation plan website on their individual jurisdictional websites to increase avenues of public access to the plan. Santa Clara County OES has agreed to maintain the hazard mitigation plan website. This site will not only house the final plan, it will become the one-stop shop for information regarding the plan, the partnership and plan implementation. Upon initiation of future update processes, a new public involvement strategy will be initiated based on guidance from a new working group. This strategy will be based on the needs and capabilities of the planning partnership at the time of the update. At a minimum, this strategy will include the use of local media outlets within the OA.

Through this planning process, the Working Group recognized a need to develop a crisis communication strategy. The Working Group identified the benefit of a sole-source outlet for providing public information. During the planning process, the Santa Clara County Fire Department's public information officer provided guidance to jurisdictional public information officers in regards to messaging and public response via social media. During the performance period, a single messaging system to be designated by Santa Clara County OES will be established on behalf of the whole partnership.

INCORPORATION INTO OTHER PLANNING MECHANISMS
The information on hazard, risk, vulnerability, and mitigation contained in this plan is based on the best science and LeclUlology available at the time this plan was prepared. The general plans of the planning partners are considered to be integral parts of this plan. The planning partners, through adoption of general plans and zoning ordinances, have planned for the impact of natural hazards. The plan development process provided them with the opportunity to review and expand on policies contained within these planning mechanisms. The planning partners used their general plans and the hazard mitigation plan as complementary documents that work together to achieve the goal of reducing risk exposure to the citizens of the OA. An update to a general plan may trigger an update to the hazard mitigation plan .

All municipal planning partners are committed to creating a linkage between the hazard mitigation plan and their individual general plans by identifying a mitigation action as such and giving that action a high priority. Additionally, all planning partners are committed to being in full compliance with California Assembly Bill 2140 and Senate Bill 379, which promote the integration of local hazard mitigation plans and general plans and mandate that these plans address climate change. Other planning processes and programs to be coordinated with the recommendations of the hazard mitigation plan include the following:
• Emergency response plans.
• Training and exercise of emergency response plans.
• Debris Management Plans.
• Recovery Plans.
• Capital improvement programs.
• Municipal codes .
• Community design guidelines.
• Water-efficient landscape design guidelines.
• Stormwater management programs.
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• Water system vulnerability assessments.
• Community Wildfire Protection Plans.
• Comprehensive Flood Hazard Management Plans.
• Resiliency Plans.
• Community Development Block Grant-Disaster Recovery action plans. • Public information/Education plans.

Some action items do not need to be implemented through regulation. Instead, these items can be implemented through the creation of new educational programs, continued interagency coordination, or improv ed public participation. As information becomes available from other planning mechanisms that can enhanc e this plan, that information will be incorporated via the update process. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 325

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https :llwaterdata.usgs.gov I cal nwis! current! ?type=flow&group key=county cd " U.S. Geological Survey (USGS). 2017c. Land Subsidence: Cause & Effect. Page of the USGS web site.

Accessed online at h ttps : II ca. water. usgs . gOY /land subsidence I cali fornia-subsidence -ca use­ effect.html
U.S. Global Change Research Program (USGCRP). 2009. Global Climate Change Impacts in the United States, Thomas R. Karl, Jerry M. Melillo and Thomas C. Peterson, (eds.). Cambridge University Press. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 329

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GLOSSARY

ACRONYMS
OF
ABAG
ADA
API
ASPA
ATC
BACERP
BART
BPR

CAL FIRE
CalOES
CCR
CDC
CEQA
CERCLA
CFR
cfs
CPUC
CRS
CSA
CWA
CZM
DART
DEM
DFIRM
DHS
DMA
DOF
DWR
EA
EMA
EMP
EPA
EPCRA
ESA
FAA
FBI
FEMA
FERC
FHSZ
FIRM
FMA
FRA
330 I Page
- Degrees Fahrenheit
- Association of Bay Area Governments
- Americans with Disabilities Act
- Advanced Persistent Threat
- Aboveground petroleum storage tank
- (Federal) Air Traffic Controller
- Bay Area Climate and Energy Resilience Project
- Bay Area Rapid Transit System
- Bottom pressure recorder
-California Department of Forestry and Fire Protection
-California Office of Emergency Services
- California Code of Regulations
- Centers for Disease Control and Prevention
-California Environmental Quality Act
-Comprehensive Environmental Response, Compensation, and Liability Act - Code of Federal Regulations
- cubic feet per second
-California Public Utilities Commission
-Community Rating System
- County Service Area
-Clean Water Act
- Coastal Zone Management
- Deep ocean Assessment and Reporting of Tsunamis
- Digital Elevation Model
- Digital Flood Insurance Rate Maps
- Department of Homeland Security
- Disaster Mitigation Act
- Department of Finance
- Department of Water Resources
- Electronic Attack
- Emergency Managers Association
- Electromagnetic Pulse
- U.s. Environmental Protection Agency
- Emergency Planning and Community Right to Know Act
- Endangered Species Act
- Federal Aviation Administration
- Federal Bureau of Investigation
- Federal Emergency Management Agency
- Federal Energy Regulatory Commission
- Fire Hazard Severity Zone
- Flood Insurance Rate Map
- Flood Mitigation Insurance
- Federal responsibility area
Santa Clara County Operational Area Mitigation Plan 10/15/17

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FRAP
g
GIS
gpcd
Hazus
HMGP
HMI
HMP
IBC
IPCC
IRC
ISO
IT
LEPC
LHMP
LiMWAN
LRA
m
MCI
MITM
mm
MM
mm/yr
MM
mph
NASA
NCDC
NCRIC
NDSP
NEHRP
NFIP
NFPA
NLD
NMDC
NOAA
NTSC
NWS
ONI
PCB
POI
PDM
PDSI
PG&E
PGA
PHDI
PTWC
RCRA
10/15/17
- Fire and Resource Assessment
-Gravity (%g, percent acceleration force of gravity)
-Geographic Information System
- Gallons per capita per day
-Hazards, United States-Multi Hazard
- Hazard Mitigation Grant Program
-Hazard Mitigation Insurance
- Hazard Mitigation Plan
- International Building Code
- Intergovernmental Panel on Climate Change
- International Residential Code
- Insurance Services Office
-Information Technology
- Local emergency planning committee
- Local hazard mitigation plan
- Limit of Moderate Wave Action
- Local responsibility area
-Meter
- Mass casualty incident
- Man in the middle
- Millimeter
- Modified Mercalli
- Millimeters per year
- Modified Mercalli Scale
- Miles per hour
-National Aeronautics and Space Administration
- National Climatic Data Center
-Northern California Regional Intelligence Center
-National Dam Safety Program
-National Earthquake Hazard Reduction Program
- National Flood Insurance Program
-National Fire Protection Academy
-National Levee Database
-National Drought Mitigation Center
-National Oceanic and Atmospheric Administration
-National Transportation Safety Board
-National Weather Service
- Ocean Nino Index
- Polychlorinated biphenyls
- Palmer Drought Index
-Pre-Disaster Mitigation Grant Program
- Palmer Drought Severity Index
- Pacific Gas and Electric
- Peak Ground Acceleration
- Palmer Hydrological Drought Index
-Pacific Tsunami Warning Center
- Resource Conservation and Recovery Act
Santa Clara County Operational Area Mitigation Plan Page I 331 SCA -(Bay Area Water) Supply Conservation Agency
SCADA -Supervisory Control and Data Acquisition
SERC -State Emergency Response Commission
SFHA - Special Flood Hazard Area
SFO -San Francisco International Airport
SFPUC -San Francisco Public Utilities Commission

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SHELDUS -Special Hazard Events and Losses Database for the US SPCC - Spill Prevention Control and Countermeasures
SPI -Standardized Precipitation Index
SRA -State responsibility area
TSCA - Toxic Substances Control Act
UN - United Nations
USDA - United States Department of Agriculture
USGS - U.S. Geological Survey
UST - Underground storage tank
VHFHSZ - Very High Fire Hazard Severity Zone
WCI ATWC - West Coast and Alaskan Tsunami Warning Center WMD - Weapons of Mass Destruction

DEFINITIONS
lOO-Year Flood: The term "IOO-year flood" can be misleading. The 100-year flood does not necessarily occur once every 100 years. Rather, it is the flood that has a I percent chance of being equaled or exceeded in any given year. Thus, the IOO-year flood could occur more than once in a relatively short period of time. The Federal Emergency Management Agency (FEMA) defines it as the 1 percent annual chance flood, which is now the standard definition used by most federal and state agencies and by the National Flood Insurance Program (NFIP).

Acre-Foot: An acre-foot is the amount of water it takes to cover I acre to a depth of 1 foot. This measure is used to describe the quantity of storage in a water reservoir. An acre-foot is a unit of volume. One acre foot equals 7,758 barrels; 325,829 gallons; or 43,560 cubic feet. An average household of four will use approximately I acre-foot of water per year.

Asset: An asset is any man-made or natural feature that has value, including people; buildings; infrastructure, such as bridges, roads, sewers, and water systems; lifelines, such as electricity and communication resources; and environmental, cultural, or recreational features such as parks, wetlands, and landmarks.

Base Flood: The flood having a I % chance of being equaled or exceeded in any given year, also known as the "IOO-year" or "I % chance" flood. The base flood is a statistical concept used to ensure that all properties subject to the National Flood Insurance Program (NFIP) are protected to the same degree against flooding.

Basin: A basin is the area within which all surface water - whether from rainfall, snowmelt, springs, or other sources-flows to a single water body or watercourse. The boundary of a river basin is defined by natural topography, such as hills, mountains, and ridges. Basins are also referred to as "watersheds" and "drainage basins."
Benefit: A benefit is a net project outcome and is usually defined in monetary terms. Benefits may include direct and indirect effects. For the purposes of benefit-cost analysis of proposed mitigation measures, 332 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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benefits are limited to specific, measurable, risk reduction factors, including reduction in expected property losses (buildings, contents, and functions) and protection of human life.

Benefit/Cost Analysis: A benefitj cost analysis is a systematic, quantitative method of comparing projected benefits to projected costs of a project or policy. It is used as a measure of cost effectiveness.

Building: A building is defined as a structure that is walled and roofed, principally aboveground, and permanently fixed to a site. The term includes manufactured homes on permanent foundations on which the wheels and axles carry no weight.

Capability Assessment: A capability assessment provides a description and analysis of a community's current capacity to address threats associated with hazards. The assessment includes two components:
an inventory of an agency's mission, programs, and policies, and an analysis of its capacity to carry them out. A capability assessment is an integral part of the planning process in which a community's actions to reduce losses are identified, reviewed, and analyzed, and the framework for implementation is identified. The following capabilities were reviewed under this assessment:
• Legal and regulatory capability
• Administrative and technical capability
• Fiscal capability
Community Rating System (CRS): The CRS is a voluntary program under the NFIP that rewards participating communities (provides incentives) for exceeding the minimum requirements of the NFIP and completing activities that reduce flood hazard risk by providing flood insurance premium discounts.

Critical Area: An area defined by state or local regulations as deserving special protection because of unique natural features or its value as habitat for a wide range of species of flora and fauna. A sensitive/ critical area is usually subject to more restrictive development regulations.

Critical Facility: Facilities and infrastructure that are critical to the health and welfare of the population.

These become especially important after any hazard event occurs. For the purposes of this plan, critical facilities include:
• Structures or facilities that produce, use, or store highly volatile, flammable, explosive, toxic and/ or water reactive materials;
• Hospitals, nursing homes, and housing likely to contain occupants who may not be sufficiently mobile to avoid death or injury during a hazard event. • Police stations, fire stations, vehicle and equipment storage facilities, and emergency operations centers that are needed for disaster response before, during, and after hazard events, and
• Public and private utilities, facilities and infrastructure that are vital to maintaining or restoring normal services to areas damaged by hazard events. • Government facilities.

Cubic Feet per Second (cfs): Discharge or river flow is commonly measured in cfs. One cubic foot is about 7.5 gallons of liquid.

Dam: Any artificial barrier or controlling mechanism that can or does impound 10 acre-feet or more of water.

Dam Failure: Dam failure refers to a partial or complete breach in a dam (or levee) that impacts its integrity. Dam failures occur for a number of reasons, such as flash flooding, inadequate spillway size, 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 333

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mechanical failure of valves or other equipment, freezing and thawing cycles, earthquakes, and intentional destruction.

Debris Avalanche: Volcanoes are prone to debris and mountain rock avalanches that can approach speeds of 100 mph .

Debris Flow: Dense mixtures of water-saturated debris that move down-valley; looking and behaving much like flowing concrete. They form when loose masses of unconsolidated material are saturated, become unstable, and move down slope. 'Ilhe source of water varies but includes rainfall, melting snow or ice, and glacial outburst floods.

Debris Slide: Debris slides consist of unconsolidated rock or soil that has moved rapidly down slope.

They occur on slopes greater than 65 percent.

Disaster Mitigation Act of 2000 (DMA); The DMA is Public Law 106-390 and is the latest federal legislation enacted to encourage and promote proactive, pre-disaster planning as a condition of receiving financial assistance under the Robert T. Stafford Act. The DMA emphasizes planning for disasters before they occur. Under the DMA, a pre-disaster hazard mitigation program and new requirements for the national post-disaster hazard mitigation grant program (HMGP) were established.

Drainage Basin: A basin is the area within which all surface water- whether from rainfall, snowmelt, springs or other sources- flows to a single water body or watercourse. The boundary of a river basin is defined by natural topography, such as hills, mountains and ridges. Drainage basins are also referred to as watersheds or basins.

Drought: Drought is a period of time without substantial rainfall or snowfall from one year to the next.

Drought can also be defined as the cumulative impacts of several dry years or a deficiency of precipitation over an extended period of time, which in turn results in water shortages for some activity, group, or environmental function. A hydrological drought is caused by deficiencies in surface and subsurface water supplies. A socioeconomic drought impacts the health, well-being, and quality of life or starts to have an adverse impact on a region. Drought is a normal, recurrent feature of climate and occurs almost everywhere.

Earthquake: An earthquake is defined as a sudden slip on a fault, volcanic or magmatic activity, and sudden stress changes in the earth that result in ground shaking and radiated seismic energy.

Earthquakes can last from a few seconds to over 5 minutes, and have been known to occur as a series of tremors over a period of several days. The actual movement of the ground in an earthquake is seldom the direct cause of injury or death. Casualties may result from falling objects and debris as shocks shake, damage, or demolish buildings and other structures.

Exposure: Exposure is defined as the number and dollar value of assets considered to be at risk during the occurrence of a specific hazard.

Extent: The extent is the size of an area affected by a hazard.

Fire Behavior: Fire behavior refers to the physical characteristics of a fire and is a function of the interaction between the fuel characteristics (such as type of vegetation and structures that could burn), topography, and weather. Variables that affect fire behavior include the rate of spread, intensity, fuel consumption, and fire type (such as underbrush versus crown fire).

Fire Frequency: Fire frequency is the broad measure of the rate of fire occurrence in a particular area. An estimate of areas most likely to burn is based on past fire history or fire rotation in the area, fuel 3341 Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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conditions, weather, ignition sources (such as human or lightning), fire suppression response, and other factors.

Flash Flood: A flash flood occurs with little or no warning when water levels rise at an extremely fast rate
Flood Insurance Rate Map (FIRM): FIRMs are the official maps on which the Federal Emergency Management Agency (FEMA) has delineated the Special Flood Hazard Area (SFHA).

Flood Insurance Study: A report published by the Federal Insurance and Mitigation Administration for a community in conjunction with the community's Flood Insurance rate Map. The study contains such background data as the base flood discharges and water surface elevations that were used to prepare the FIRM. In most cases, a community FIRM with detailed mapping will have a corresponding flood insurance study.

Floodplain: Any land area susceptible to being inundated by flood waters from any source. A flood insurance rate map identifies most, but not necessarily all, of a community's floodplain as the Special Flood Hazard Area (SFHA).

Floodway: Floodways are areas within a floodplain that are reserved for the purpose of conveying flood discharge without increasing the base flood elevation more than 1 foot. Generally speaking, no development is allowed in floodways, as any structures located there would block the flow of floodwaters.

Floodway Fringe: Floodway fringe areas are located in the floodplain but outside of the floodway. Some development is generally allowed in these areas, with a variety of restrictions. On maps that have identified and delineated a floodway, this would be the area beyond the floodway boundary that can be subject to different regulations.

Fog: Fog refers to a cloud (or condensed water droplets) near the ground. Fog forms when air close to the ground can no longer hold all the moisture it contains. Fog occurs either when air is cooled to its dew point or the amount of moisture in the air increases. Heavy fog is particularly hazardous because it can restrict surface visibility. Severe fog incidents can close roads, cause vehicle accidents, cause airport delays, and impair the effectiveness of emergency response. Financial losses associated with transportation delays caused by fog have not been calculated in the United States but are known to be substantial.

Freeboard: Freeboard is the margin of safety added to the base flood elevation.

Frequency: For the purposes of this plan, frequency refers to how often a hazard of specific magnitude, duration, and/ or extent is expected to occur on average. Statistically, a hazard with a 100-year frequency is expected to occur about once every 100 years on average and has a 1 percent chance of occurring any given year. Frequency reliability varies depending on the type of hazard considered.

Fujita Scale of Tornado Intensity: Tornado wind speeds are sometimes estimated on the basis of wind speed and damage sustained using the Fujita Scale. The scale rates the intensity or severity of tornado events using numeric values from FO to F5 based on tornado wind speed and damage. An FO tornado (wind speed less than 73 miles per hour (mph» indicates minimal damage (such as broken tree limbs), and an F5 tornado (wind speeds of 261 to 318 mph) indicates severe damage.

Goal: A goal is a general guideline that explains what is to be achieved. Goals are usually broad-based, long-term, policy-type statements and represent global visions. Goals help define the benefits that a plan 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 335

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is trying to achieve. The success of a hazard mitigation plan is measured by the degree to which its goals have been met (that is, by the actual benefits in terms of actual hazard mitigation) .

Geographic Information System (GIS): GIS is a computer software application that relates data regarding physical and other features on the earth to a database for mapping and analysis.

Hazard: A hazard is a source of potential danger or adverse condition that could harm people and/ or cause property damage.

Hazard Mitigation Grant Program (HMGP): Authorized under Section 202 of the Robert T. Stafford Disaster Relief and Emergency Assistance Act, the HMGP is administered by FEMA and provides grants to states, tribes, and local governments to implement hazard mitigation actions after a major disaster declaration. The purpose of the program is to reduce the loss of life and property due to disasters and to enable mitigation activities to be implemented as a community recovers from a disaster Hazards U.S. Multi-Hazard (Hazus) Loss Estimation Program: Hazus is a GIS-based program used to support the development of risk assessments as required under the DMA. The Hazus software program assesses risk in a quantitative manner to estimate damage and losses associated with natural hazards.

Hazus is FEMA's nationally applicable, standardized methodology and software program and contains modules for estimating potential losses from earthquakes, floods, and wind hazards. Hazus has also been used to assess vulnerability (exposure) for other hazards.

Hydraulics: Hydraulics is the branch of science or engineering that addresses fluids (especially water) in motion in rivers or canals, works and machinery for conducting or raising water, the use of water as a prime mover, and other fluid-related areas.

Hydrology: Hydrology is the analysis of waters of the earth. For example, a flood discharge estimate is developed by conducting a hydrologic study.

Intensity : For the purposes of this plan, intensity refers to the measure of the effects of a hazard.

Inventory: The assets identified in a study region comprise an inventory . Inventories include assets that could be lost when a disaster occurs and community resources are at risk. Assets include people, buildings, transportation, and other valued community resources.

Landslide: Landslides can be described as the sliding movement of masses of loosened rock and soil down a hillside or slope. Fundamentally, slope failures occur when the strength of the soils forming the slope exceeds the pressure, such as weight or saturation, acting upon them.

Lightning: Lightning is an electrical discharge resulting from the buildup of positive and negative charges within a thunderstorm. When the buildup becomes strong enough , lightning appears as a "bolt," usually within or between clouds and the ground. A bolt of lightning instantaneously reaches temperatures approaching 50,OOO"F. The rapid heating and cooling of air near lightning causes thunder.

Lightning is a major threat during thunderstorms. In the United States, 75 to 100 Americans are struck and killed by lightning each year (see http://www .fema.gov/hazard/thunderstorms I thunder .sh tm).

Liquefaction: Liquefaction is the complete failure of soils, occurring when soils lose shear strength and flow horizontally. It is most likely to occur in fine grain sands and silts, which behave like viscous fluids when liquefaction occurs . This situation is extremely hazardous to development on the soils that liquefy, and generally results in extreme property damage and threats to life and safety .

Local Government: Any county, municipality, city, town, township, public authority, school district, special district, intrastate district, council of governments (regardless of whether the council of 336 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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governments is incorporated as a nonprofit corporation under State law), regional or interstate government entity, or agency or insh'umentality of a local govenunent; any Indian tribe or authorized tribal organization, or Alaska Native village or organization; and any rural community, unincorporated town or village, or other public entity.

Magnitude: Magnitude is the measure of the strength of an earthquake, and is typicaUy measured by the Richter scale. As an estimate of energy, each whole number step in the magnitude scale corresponds to the release of about 31 times more energy than the amount associated with the preceding whole number value.

Mass movement: A collective term for landslides, debris flows, and lahars.

Mitigation: A preventive action that can be taken in advance of an event that will reduce or eliminate the risk to life or property.

Mitigation Actions: Mitigation actions are specific actions to achieve goals and objectives that minimize the effects from a disaster and reduce the loss of life and property.

Objective: For the purposes of this plan, an objective is defined as a short-term aim that, when combined with other objectives, forms a strategy or course of action to meet a goal. Unlike goals, objectives are specific and measurable.

Peak Ground Acceleration: Peak Ground Acceleration (PGA) is a measure of the highest amplitude of ground shaking that accompanies an earthquake, based on a percentage of the force of gravity.

Preparedness: Preparedness refers to actions that strengthen the capability of government, citizens, and communities to respond to disasters.

Presidential Disaster DecIaration: These declarations are typically made for events that cause more damage than state and local governments and resources can handle without federal government assistance. Generally, no specific dollar loss threshold has been established for such declarations. A Presidential Disaster Declaration puts into motion long-term federal recovery programs, some of which are matched by state programs, deSigned to help disast eT victims, businesses, and public entities.

Probability of Occurrence: The p.robability of occurrence is a statistical measure or estimate of the likelihood that a hazard will occur. This probability is generally based on past hazard events in the area and a forecast of events that could occur in the future. A probability factor based on yearly values of occurrence is used to estimate probability of occurrence.

Repetitive Loss Property: Any NFIP-insul'ed property that, since 1978 and regardless of any changes of ownership during that period, has experienced:
• Four or more paid flood losses in excess of $1000.00; or • Two paid flood losses in excess of $1000.00 within any 10-year period since 1978 or • Three or more paid losses that equal or exceed the current value of the insured property.

Return Period (or Mean Return Period): This term refers to the average period of time in years between occurrences of a particular hazard (equal to the inverse of the annual frequency of occurrence).

Riverine: Of or produced by a river. Riverine floodplains have readily identifiable channels. Floodway maps can only be prepared for riverine floodplains.

Risk: Risk is the estimated impact that a hazard would h.ave on people, services, facilities, and structur es in a community. Risk measures the likelihood of a hazard occurring and resulting in an adverse condition 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 337

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that causes injury or damage. Risk is often expressed in relative terms such as a high, moderate, or low likelihood of sustaining damage above a particular threshold due to occurrence of a specific type of hazard. Risk also can he expressed in terms of potential monetary losses associated with the intensity of the hazard .

Risk Assessment: Risk assessment is the process of measuring potential loss of life, personal injury, economic injury, and property damage resulting from hazards. This process assesses the vulnerability of people, buildings, and infrastructure to hazards and focuses on (1) hazard identification; (2) impacts of hazards on physical, social, and economic assets; (3) vulnerability identification; and (4) estimates of the cost of damage or costs that could be avoided through mitigation.

Risk Ranking : This ranking serves two purposes, first to describe the probability that a hazard will occur, and second to describe the impact a hazard will have on people, property, and the economy. Risk estimates are based on the methodology used to prepare the risk assessment for this plan. The following equation shows the risk ranking calculation:

Risk Ranking = Probability + Impact (people + property + economy) Robert T. Stafford Act: The Robert T. Stafford Disaster Relief and Emergency Assistance Act, Public Law 100-107, was signed into law on November 23, 1988. This law amended the Disaster Relief Act of 1974, -ru blic Law 93-288. The Stafford Act is the statutory authority for most federal disaster response activities, especially as they pertain to FEMA and its programs.

Special Flood Hazard Area: The base floodplain delineated on a Flood Insurance Rate Map. The SFHA is mapped as a Zone A in riverine situations and zone V in coastal situations. The SFHA mayor may not encompass all of a community's flood problems
Stakeholder: Any person or public or private entity that owns or operates facilities that would benefit from the mitigation actions of this plan, and/ or has an authority or capability to support mitigation actions identified by this plan.

Stream Bank Erosion: Stream bank erosion is common along rivers, streams and drains where banks have been eroded, sloughed or undercut . However, it is important to remember that a stream is a dynamic and constantly changing system. It is natural for a stream to want to meander, so not all eroding banks are "bad" and in need of repair. Generally, stream bank erosion becomes a problem where development has limited the meandering natUJ'e of streams, where sb'eams have been channelized, or where stream bank structures (like bridges, culverts, etc.) are located in places where they can actually cause damage to downstream areas. Stabilizing these areas can help protect watercourses from continued sedimentation, damage to adjacent land uses, conb'ol unwanted meander, and improvement of habitat for fish and wildlife.

Steep Slope: Different communities and agencies define it differently, depending on what it is being applied to, but generally a steep slope is a slope in which the percent slope equals or exceeds 25%. For this study, steep slope is defined as slopes greater than 33%.

Thunderstorm: A thunderstorm is a storm with lightning and thunder produced by cumulonimbus clouds. Thunderstorms usually produce gusty winds, heavy rains, and sometimes hail. Thunderstorms are usually short in duration (seldom more than 2 hours) . Heavy rains associated with thunderstorms can lead to flash flooding during the wet or dry seasons.

Tornado: A tornado is a violently rotating column of air extending between and in contact with a cloud and the surface of the earth. Tornadoes are often (but not always) visible as funnel clouds. On a local 338 I Page Santa Clara County Operational Area Mitigation Plan 10/15/17

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scale, tornadoes are the most intense of all atmospheric circulations, and winds can reach destructive speeds of more than 300 mph. A tornado's vortex is typically a few hundred meters in diameter, and damage paths can be up to 1 mile wide and 50 miles long.

Vulnerability: Vulnerability describes how exposed or susceptible an asset is to damage. Vulnerability depends on an asset's construction, contents, and the economic value of its functions. Like indirect damage, the vulnerability of one element of the community is often related to the vulnerability of another.

For example, many busin .esses depend on uninterrupted electrical power. Flooding of an electric substation would affect not only the substation itself but businesses as well. Often, indirect effects can be much more widespread and damaging than direct effects.

Watershed: A watershed is an area that drains downgradient from areas of higher land to areas of lower land to the lowest point, a common drainage basin.

Wildfire: These terms refer to any uncontroll ed fue occurring on undeveloped land that requires fire suppression. The potential for wildfire is influenced by three factors: the presence of fuel, topography, . and air mass. Fue l can include Living and dead vegetation on the ground, along the surface as brush and small trees, and in the air such as tree canopies. Topography includes both slope and elevation. Air mass includes temperature, relative humidity, wind speed and direction, cloud cover, precipitation amount, duration, and the stability of the atmosphere at the time of the fire. Wildfires can be ignited by Lightning and, most frequently, by human activity including smoking, campfires, equipment use, and arson.

Windstorm: Windstorms are generally short-duration events involving straight-line winds or gusts exceeding 50 mph. These gusts can produce winds of sufficient strength to cause property damage.

Windstorms are esp ecially dangerous in areas with significant tree stands, exposed property, poorly constructed buildings, mobile homes (manufactured housing units), major infrastructme, and aboveground utility lines. A windstorm can topple b·ees and power lines; ca use damag e to resid ential, commercial, critical facilities; and leave tons of debris in its wake.

Zoning Ordinance: The zoning ordinance designates allowable land use and intensities for a local jurisdiction . Zorling ordinances consist of two components: a zoning text and a zoning map. 10/15/17 Santa Clara County Operational Area Mitigation Plan Page I 339 340 I Page

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ApPENDIX A: PUBLIC OUTREACH MATERIALS
Santa Clara County Operational Area Mitigation Plan 10/15/17 Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Ql Which of the following natural hazard events have you, your place of employment, your school, or anyone in your household experienced within the past 20 years in the Santa Oara Operational Area? (Check all that apply) Answer Choices
Drought
Earthquake
Drought
Earthquake
Severe Weather
(high wind, ...

Flood
None
Wildfire
Landslide & I
Mass Movemen ...

Other (please
specify)
Dam/Levee I
Failure
Tsunami
0% 10%
Severe Weather (high wind, heavy rain, lightning, etc.) Flood
None
Wildfire
Landslide & Mass Movements (sinkholes, geologic hazards) Answered: 2,065 Skipped: 27
20% 30% 40% 50% 60% 70% 80% 90% 100%
Responses

70.31'10 1.452

69.08'10 1.220

42.81'10 884

12.40'10 256

12.20'10 252

9.73'10 201

4.07'10 84
lof31
Other (please specify)
Dam/Levee Failure
Tsunami
Total Respondents: 2,065
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey

3.78%

1.31%

0.53%
78 27
11 Q2 How concerned are you about the following natural hazards in Santa Clara Operational Area? (Please check one for each hazard)
Earthquake
Drought
Wildfire
Earthquake
Drought
Wildfire
Severe Weather
(wind, ...

Landslide & Other
Earth ..•
Flood
Dam/Levee
Failure
Other Natural
Hazard
Tsunami
o
Severe Weather (wind, lightning, fog, heavy rains,
solar flare, etc.)
Answered: 2,081 Skipped : 11
2 3 4 5 6
Not Somewhat Concerned
concerned concerned

0.78% 7.20% 22.53%
16 148 463

2.22% 12.28% 25.01%
45 249 507

28.14% 26.93% 22.46%
560 536 447

19.35% 35.33% 30.27%
390 712 610
2of31
7 8 9 10
Very Extremely Total Weighted
concerned concerned Average

35.28% 34.21%
725 703 2,055 3.95

35.03% 25.46%
710 516 2.027 3.69

13.27% 9.20%
264 183 1,990 2.48

10.47% 4.57%
211 92 2.015 2.46
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Landslide & Other Earth Movements 35.31% 34.56% 19.95% 6.60% 3.58% (sinkholes.geologic hazard) 701 686 396 131 71 1,985 2.09 Flood 28.19% 34,87% 24.32% 9.45% 3.17%
561 694 484 188 63 1,990 225
Dam/Levee Failure 51.70% 28.96% 11.99% 4.84% 2.52%
1,005 563 233 94 49 1,944 178
Other Natural Hazard 57.54% 20.290/0' 15,73% 3.58% 2.86% 885 312 I 242 55 44
Tsunami 73,03%' 18.78% 6.02%' 1.16% 1.01"1.
1,443 371 119 23 20
Q3 The FEMA website - Ready.gov - provides important information on how to prepare you and your family in the event of a disaster. How prepared is your household for a natural or human-caused hazard event? (Check one) Answered: 2,072 Skipped: 20
Not at all Prepared
Somewhat Prepared
Adequately Prepared
Well Prepared
Very Well Prepared
0% 10% 20% 30% 40% 50% 60% 70% BO% 90% 100%
Answer ChOices Responses
Not at all Prepared 10.28% 213
Somewhat Prepared 53.72% 1,113
Adequately Prepared 22.92% 475
Well Prepared 9.99% 207
Very Well Prepared 3.09% 64
Total 2,072
3 of 31
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q4 How would you expect to be notified in case of an immediate threat caused by a natural or human-caused hazard.

Select all that apply.

Answer Choices
Television
Radio
Facebook
Twitter
Nextdoor
Nixie
AlertSCC
Other (please specify)
Total Respondents: 2,069
Television
Radio
Facebook
Twitter
Nextdoor
Nixie
AlertSCC
Other (please
specify)
0% 10% 20%
Answered : 2,069 Skipped : 23
30% 40% 50% 60% 70% 60% 90% 100%
Responses

67.91% 1,405

75.25% 1.557

30.26% 626

13.68% 283

54.18% 1,121

16.58% 343

56.50% 1,169

26.58% 550
4 of 31
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q5 FEMA suggests that households have at least 3 days of food, water, and vital supplies (e.g. medications) in hand in the event of a disaster. How many days of food, water, and vital supplies does your household have on hand in the event of a disaster?
Answered : 2,070 Skipped : 22
2 3
4 5
6 7
8 10
None
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Answer Choices Responses

6.91% 143
2 12.71% 263
3 27.49% 569
4 6.09% 126
5 14.25% 295
6 2.51% 52
7 14.06% 291
8 1.79% 37
50f31
9 10
None
Total
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey

0.43%

10.87%

2.90%
Q6 How prepared is your household to get along without electricity or natural gas for one to five days? Answered: 2,070 Skipped : 22
Not at aU prepared
Somewhat prepared
Very prepared
0% 10% 20% 30% 40% 50% 60% 70% BO% 90% 100%
Answer Choices Responses
Not at all prepared 19.86%
Somewhat prepared 60.00%
Very prepared 20.14%
Total
6of31
9 225
60 2,070
411

1.242
417
2,070
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q7 Where would you expect to find useful information to help you be prepared? Select all that apply.

Answer Choices
Television
Internet
Social Media
Television
Internet
Social Media
Newspaper/magazine
Public government..

Schools/academic
institutions
Other (please
specify)
Newspaper/magazine
Public government meetings
Schools/academic institutions
Other (please specify)
Total Respondents: 2,060
0%
Answered: 2,060 Skipped: 32
10% 20% 30% 40% 50% 60% 70% 60% 90% 100%
Responses

37.82%

91.17%

28.45%

39.95%

33.93%

21.46%

15.78%
7of31
779

1.676
566
623
699
442
325
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q8 Which of the following steps has your household already undertaken to prepare for a disaster? Select all that apply.

Answered: 2,055 Skipped: 37
Rece ive
Prepared a
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Answer Choices Responses
Received first aid/CPR training 56.50% 1.161
Made a fire escape plan 37.62% 773
Designated a meeting place 33.77% 694
Identified utility shutoffs 71.82% 1.476
Community Emergency Response Training (CERT) 23.99% 493 Prepared a disaster supply kit 51.78% 1,064
Installed smoke detectors on each level of the house 92.65% 1,904

74.36% 1.528
Stored food and water
Stored flashlights and batteries 83.45% 1,715
Stored a battery-powered radio 56.06% 1,152
8of31
Stored a fire extinguisher
Stored medical supplies (first aid kit, medications)
Other (please specify)
Tota. Respondents: 2,055
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
9 of 31
71,24% 1,464
71,92% 1,478
9,05% 186
Q9 Where do you live?
Campbell
Cupertino
Gilroy
I do not live in Santa Clara
Los Altos
Los Altos Hills
Los Gatos
Milpitas
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey
I
•
I
Answered: 2,083 Skipped: 9
Monte Sereno ,
Morgan HIli
Mountain View
Palo Alto
San Jose
Santa Clara
(City)
Santa Clara (County) I
Saratoga
Sunnyvala
0% 10% 20% 30% 40% 50% 60% 70%
10 of 31
80% 90% 100%
Answer Choices
Campbell
Cupertino
Gilroy
I do not live in Santa Clara County.

Los Altos
Los Altos Hills
Los Gatos
Milpitas
Monte Sereno
Morgan Hill
Mountain View
Palo Alto
San Jose
Santa Clara (City)
Santa Clara (County - Unincorporated)
Saratoga
Sunnyvale
Total
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
11 of31
Responses

5.95%

4.75%

0.24%

0.82%

6.00%

4.75%

4.61%

0.05%

0.62%

3.31%

5.57%

14.21%

20.21°,,;

5.90%

2.40%

4.22%

16.37%
124
99 5
17 125
99 96
13 69
116
296
421
123
50 88
341
2,083
QI0 Where do you work?
Campbell
Cupertino
Gilroy
Los Altos I
Los Altos Hills I
Los Gatos
Milpitas I
Monte Sereno
Morgan Hili I
Mountain View
Palo Alto
San Jose
Santa Clara
(City)
Santa Clara
I (County)
Saratoga I
Sunnyvale
I do not work in Santa
Clara
0%
Answer Choices
Campbell
Cupertino
Gilroy
Los Altos
Los Altos Hills
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Answered: 1,967 Skipped : 125
10% 20% 30% 40% 50% 60% 70%
12of31
80% 90% 100%
Responses

2.80% 55

4.68% 92

0.31% 6

2.49% 49

1.47% 29
Los Gatos
Milpitas
Monte Sereno
Morgan Hill
Mountain View
Palo Alto
San Jose
Santa Clara (City)
Santa Clara (County - Unincorporated)
Saratoga
Sunnyvale
I do not work in Santa Clara County.

Total
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey
13 of 31

2.89% 53

0.97% 19

0.16% 3

1.27% 25

7.12% 140

11.34% 223

18.47% 324

8.91% 136

0.86% 17

1.47% 29

10.78% 212

28.22% 555
1,967
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Ql1 Do you own or rent your place of residence?
Answered: 2,020 Skipped: 72
Own
Rent
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Own 87.08%
Rent 12.92%
Total
14of31
80% 90% 100%
1,759
261
2,020
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q12 How long have you lived in at your current residence? Answered: 2,031 Skipped: 61
I don't live
0% 1U% lU% :lU'l'o 4U% bU"'/o oU% fUU/o
Answer Choices
Less than a year
1 - 2 years
3 - 5 years
6 - 10 years
11 -15 years
16 - 20 years
More than 20 years
I don't live in Santa Clara County
Total
15 of 31
tjU% ~U% 1 UUU/o
Responses

4.73% 96

6.25% 127

13.29% 270

13.10% 266

9.85% 200

9.35% 190

43.38% 881

0.05%
2,031
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q13 Do you live in a single family or multi- family dwelling? Answered: 2,032 Skipped: 60
Single-family
Multi-family
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Single-family 88.24%
M~lli ·ramly 11.78%
Total
16 of 31
80% 90% 100%
1,793
239
2,032
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q14 How many people live at your current residence (for multi-family dwellings, please estimate total number of residents within your complex)?
Answered: 1,993 Skipped : 99
Q15 When you moved into your home, did you consider the impact a disaster could have on your home? Answered: 2,022 Skipped : 70
Yes
No
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Answer Choices Responses
Yes 61.57"10 1.245
No 38.43% 777
Total 2,022
17 of 31
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q16 Was the presence of a natural hazard risk zone (e.g., dam failure zone, flood zone, landslide hazard area, high fire risk area) disclosed to you by a real estate agent, seller, or landlord before you purchased or moved into your home?
Answered: 1,996 Skipped: 96
Yes
No
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Answer Choices Responses
Ves 37.27% 744
No 62.73% 1,252
Total 1,996
18of31
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q17 Is your residence located in or near a FEMA designated floodplain? Answered: 2,031 Skipped: 61
Yes
No
Not Sure
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Yes 15.21%
No 47.37%
Not Sure 37.42%
Total
190f31
80% 90% 100%
309
962
760
2,031
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q18 Is your residence located in a darn failure zone?
Answered: 2,025 Skipped: 67
Yes
No
Not sure
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Yes 4.40%
No 63.21%
Not sure 32.40%
Total
20of31
Bo% 90% 100%
B9
1,280
656
2,025
Q19 Do you have flood insurance?
Yes
No
Not Sure
0%
Answer Choices
Yes
No
Not Sure
Total
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Answered: 2,026 Skipped: 66
10% 20% 30% 40% 50% 60% 70%
Responses

11.06%

77.69%

11.25%
21 of 31
80% 90% 100%
224

1.574
228
2,026
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q20 Is your residence located near an earthquake fault? Answered: 2,023 Skipped : 69
Yes
No
Not Sure
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Yes 55.81%
No 16.86%
Not Sure 27.34%
Total
22of31
80% 90% 100%
1,129
341
553
2,023
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q21 Is your residence located in a high liquefaction zone? Answered : 2,027 Skipped : 65
Yes
No
Not Sure
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Yes 4.44%
No 50 . 52 ~.

Not Sure 45.04%
Total
23 of 31
60% 90% 100%
90 1,024
913
2,027
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q22 Do you have earthquake insurance?
Answered: 2,028 Skipped: 64
Yes
No
Not Sure
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Yes 27.02%
No 67.16%
Not Sure 5.82%
Total
24of31
BO% 90% 100%
54B

1.362
11B
2,028
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q23 Is your property located in an area at risk for wildfires? Answered: 2,015 Skipped: 77
Yes
No
Not Sure
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Yes 13.20%
No 69.48%
Nol Sure 17.32%
Total
25 of 31
80% 90% 100%
266
1(400
349
2,015
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q24 Is your property located in an area at risk for landslide or sinkholes? Answered: 2,020 Skipped: 72
Yes
No
Not Sure
0% 10% 20% 30% 40% 50% 60% 70%
Answer Choices Responses
Yes 4.41%
No 64.70%
Not Sure 30.89%
Total
26of31
60% 90% 100%
69 1.307
624
2,020
Santa Clara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q25 Have you ever had problems securing homeowners or renters insurance due to risks from hazards? Answered: 2,021 Skipped: 71
Yes
No
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Answer Choices Responses
Yes 2,520/.

No 97.48%
Total
27of31
51 1,970
2,021
Santa Oara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q26 How much is your gross household income?
Answer Choices
$35,000 or less
$35,001 to $69,999
$70,000 to $114,999
$115,000to $179,999
$160,000 or more
Total
$35,000 or less
$35,001 to
$69,999
$70,000 to
$114,999
$115,000 to
$179,999
$180,000 or
more
0% 10%
Answered : 1,804 Skipped: 288
20% 30% 40% 50% 60% 70%
Responses

5.65%

12.03%

22.01%

23.56%

36.75%
280f31
80% 90% 100%
102
217
397
425
663
1,804
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey
Q27 Please indicate the primary language spoken in your household .

English
Spanish/Spanish
Creole
Chinese
Vietnamese
Tagalog
Korean
Other Asian and Pacific
Slavic Languages
French
GermanlWestGermanic ...

Answer Choices
English
Spanish/Spanish Creole
Chinese
Vietnamese
Tagalog
Korean
Other (please
specify)
Other Asian and Pacific Island Languages
Slavic Languages
French
GermanlWest Germanic Languages
Other (please specify)
Answered: 2,001 Skipped: 91
0% 10% 20% 30% 40% 50% 60%
29 of 31
70% 80% 90% 100%
Responses

94.75% 1.896

0.70% 14

1.65% 33

0.00% 0

0.10% 2

0.00% 0

0.30% 6

0.15% 3

0.40% B

0.55% 11

1.40% 28
Total
Santa Gara Operational Area
2016/2017 Hazard Mitigation Plan Survey
2,001
Q28 Which of the following digital media outlets do you use and/ or subscribe to receive news and information about Santa Clara Operational Area? Select all that apply.

Answer Choices
Facebook
Twitter
Nextdoor
Facebook
Twitter
Nextdoor
E-mail and/or
text messages
AlertSCC
Nixie
San Jose
Mercury News
Other (please
specify)
E-mail and/or text messages
AlertSCC
Nixie
San Jose Mercury News
Other (please specify)
Total Respondents: 1,985
0% 10%
Answered: 1,985 Skipped: 107
20% 30% 40% 50% 60% 70% 80% 90% 100%
Responses

45.19% 897

15.11% 300