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6.4.2 PROPERTY
Table 6-3 and Table 6-4 indicates the residential property in the County exposed to coastal cliff and shoreline erosion risk, respectively.
Table 6-4: Residential Property Exposed to Coastal Cliff Erosion Risk Table 6-4
Residential Property Exposed to Coastal Cliff Erosion Risk Supervisorial
District
Sea Level Rise Scenario
25 CM 75 CM 200 CM
# Value # Value # Value
District 1 0 0 0 0 0 0
District 2 0 $0 0 $0 0 $0
District 3 0 $0 0 $0 0 $0
District 4 0 $0 0 $0 0 $0
District 5 206 $1,183,367,352 226 $1,244,106,508 253 $1,323,971,611 Total 206 $1,183,367,352 226 $1,244,106,508 253 $1,323,971,611 Table 6-5: Residential Property Exposed to Shoreline Erosion Risk Table 6-5
Residential Property Exposed to Shoreline Erosion Risk
Supervisorial
District
Sea Level Rise Scenario
25 CM 75 CM 200 CM
# Value # Value # Value
District 1 0 0 0 0 0 0
District 2 0 $0 0 $0 0 $0
District 3 0 $0 0 $0 0 $0
District 4 0 $0 0 $0 0 $0
District 5 4 $3,099,857 4 $3,099,857 4 $3,099,857
Total 4 $3,099,857 4 $3,099,857 4 $3,099,857
Table 6-6 and Table 6-7 indicates the non-residential property in the County exposed to coastal cliff and shoreline erosion risk, respectively.
Table 6-6: Non-Residential Property Exposed to Coastal Cliff Erosion Risk Table 6-6
Non-Residential Property Exposed to Coastal Cliff Erosion Risk Supervisorial
District
Sea Level Rise Scenario
25 CM 75 CM 200 CM
# Value # Value # Value
District 1 0 0 0 0 0 0
District 2 0 $0 0 $0 0 $0
District 3 0 $0 0 $0 0 $0
District 4 0 $0 0 $0 0 $0
District 5 226 $221,988,454 227 $223,536,860 248 $240,099,182 Total 226 $221,988,454 227 $223,536,860 248 $240,099,182 Packet Page 290
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Table 6-7: Non-Residential Property Exposed to Shoreline Erosion Risk Table 6-7
Non-Residential Property Exposed to Shoreline Erosion Risk Supervisorial
District
Sea Level Rise Scenario
25 CM 75 CM 200 CM
# Value # Value # Value
District 1 0 0 0 0 0 0
District 2 3 $0 2 $0 1 $0
District 3 0 $0 0 $0 0 $0
District 4 0 $122,851,855 32 $122,851,855 27 $116,279,109 District 5 21 $73,218,711 20 $73,218,711 21 $73,729,302 Total 24 $196,070,566 54 $196,070,566 49 $190,008,411
Property vulnerable to coastal erosion, generally includes low-lying coastal structures and those built close to the edge of eroding bluffs. Coastal erosion impacts on coastal property are dependent on several factors including the elevation and composition of the shoreline (i.e., wide sandy beach versus a rocky intertidal beach fronting coastal bluffs).
6.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
Critical facilities that are vulnerable to coastal erosion may include transportation and wastewater treatment and water supply infrastructure. Regional and local-serving public and utility infrastructure vulnerable to coastal erosion include roads, bridges, railroad lines and crossings, wastewater treatment plants, culverts, water lines, communication line and towers, stormwater outlets, bike lanes, bike facilities, and fiber optic lines. The Seaside Pump Station, the Monterey Interceptor Pipeline between the Seaside Pump Station and Wharf II, and M1W's land/ocean outfall junction structure are all critical facilities identified at high to moderate risk from coastal erosion.
Coastal erosion will have long-lasting impacts on the Monterey Bay region’s transportation infrastructure, threatening over 50 miles of highway, roads, and rail throughout the region including Highway 1. 28 Table 6-8 summarizes transportation infrastructure exposed to both costal cliff and shoreline erosion risk in the County.
Table 6-8: Transportation Infrastructure Exposed to Cliff and Shoreline Erosion Risk Table 6-8
Transportation Infrastructure Exposed to Coastal Cliff and Shoreline Erosion Risk Transportation Infrastructure 1 ft Sea Level Rise
(2030)
3 ft Sea Level Rise
(2060)
7 ft Sea Level Rise
(2100)
Highway/Freeway (Miles) 0 0 0
Major Road (Miles) 71 88 89
Local (Miles) 1 3 8
Railroad (Miles) 0 0 0
28 Pacific Institute, California Climate Change Center, 2009, The impacts of sea-level rise on the California coast.
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6.4.4 ENVIRONMENT
Natural features such as dune fields and coastal cliffs exist over much of the County coastline that are subject to irreversible beach and bluff erosion. A transition between the land and the sea, the shoreline is a critical habitat for nutrient cycling and supports a diversity of invertebrate fauna, surf zone fishes, shorebirds, marine mammals, and plant species, including a Federally Threatened species, such as the Western Snowy Plover.
Sandy beaches and dunes also provide important services to human communities, such as flood protection, serving as barriers to landward shoreline retreat and providing a natural protective buffer against coastal flooding. Normal erosion of coastal dunes provides a significant sediment source for beaches. Sandy beaches also are a significant source of aesthetic, recreational, and economic value to human communities. For example, the Marina sand dunes are breathtaking examples of old dunes covered in coastal scrub and native dune vegetation. Loss of sandy beach and dune habitats would have large environmental effects on Monterey County.
6.4.5 ECONOMIC IMPACT
Tourism is a major economic driver in Monterey County, and future coastal erosion could threaten popular beaches and recreational facilities. Coastal erosion could affect vertical and lateral beach access points, which would prevent residents and visitors from accessing the beach and may increase the risk of injuries. Beach tourism is important to the County’ economy and generates significant revenue as many visitors rent hotels or other accommodations, dine out or shop at area stores. Visitor-serving areas such as those on the Monterey Peninsula and in Big Sur include local businesses and hotels that benefit the local economy. These businesses depend on tourism, and cities and communities within the County benefit from sales tax revenues. Disruption of these areas due to impacts of coastal erosion could decrease economic activity and affect the local economy. Future coastal beach and bluff erosion in the County may also negatively impact coastal businesses and households and decrease coastal real estate opportunities.
Coastal bluff and cliff failure due to coastal erosion can create hazardous conditions due to roadway collapse, undermined home foundations, and damage to utilities. Natural resources with recreational and economic value may also be adversely affected. This risk is notable in the Big Sur area, where roadway failure can limit access to recreational areas for months at a time.
The County supports some of the largest dune habitats in the State, which are vulnerable to damages from erosion. As this vulnerability increases over time, damages may impact the economy of the area and impact viable coastal land uses. Dune erosion along the Monterey Bay is likely to exacerbate the risk of flooding in the lower Salinas Valley. This could increase the risk of flooding on agricultural land and threaten a major economic driver. Coastal storms can also lead to erosion impacts and severe flooding and inundation of economically important infrastructure such as harbors and buildings related to commercial and recreational fisheries.
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6.5 FUTURE TRENDS IN DEVELOPMENT
Land use and development along the County’s shoreline is governed by the California Coastal Act. Regulations under the Coastal Act are typically administered by the County and local cities through adopted Local Coastal Plans (LCP), overseen by the California Coastal Commission. The County and each incorporated city’s certified Local Coastal Plans govern land use planning and development permitting. Monterey County has four LCP segments: North County, Del Monte Forest, Carmel Area, and Big Sur Coast, which guides development in unincorporated areas.
There are also three areas of deferred certification in the County, at Fort Ord Dunes State Park, Mal Paso Beach, and Yankee Point. Each city along the Coast also as a certified Local Coastal Plan which governs land use and permitting with the coastal areas of the cities.
6.6 ISSUES
Key issues associated with coastal erosion in Monterey County include:
• The risk of costal erosion to critically important dune habitat. • The economic risk of coastal erosion on the two largest economic drivers in the County:
agriculture and tourism.
• The cumulative and compounding risk of coastal erosion along with severe winter storms, large storm surge, and wave action along the coastline is likely to lead to more dramatic erosion and exacerbate flooding in low lying areas. • Coastal bluff and cliff failure due to erosion can create hazardous conditions due to roadway collapse, bridge failure, undermined home foundations, and damage to utilities. This can lead to immobility and loss of utilities. • Future sea level rise scenarios are likely to exacerbate coastal erosion risks, but a high degree of uncertainty exists on the future risk.
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7. DAM AND LEVEE FAILURE
7.1 OVERVIEW
7.1.1 DAM FAILURE
A dam is an artificial barrier that stops or restricts the flow of water. Dams are built for a variety of uses including flood protection, power generation, agriculture, water supply, and recreation.
A dam failure is usually the result of the age of the structure, inadequate spillway capacity, or structural damage caused by an earthquake or flood. Dam failures typically occur when spillway capacity is inadequate and excess flow overtops the dam, or when internal erosion (piping) through the dam or foundation occurs. Complete failure occurs if internal erosion or overtopping results in a complete structural breach, releasing a high-velocity wall of debrisfilled water that rushes downstream, damaging anything in its path. Improper design, improper maintenance, negligent operation, and/or failure of upstream dams on the same waterway can also cause or contribute to dam failure.
Water released by a failed dam generates tremendous energy and can cause a flood that is catastrophic to life and property. A catastrophic dam failure could challenge local response capabilities and require evacuations to save lives. Impacts to life safety will depend on the warning time and the resources available to notify and evacuate the public. Major loss of life could result as well as potentially catastrophic effects to roads, bridges, and homes. Electric generating facilities and transmission lines could also be damaged and affect life support systems in communities outside the immediate hazard area. Associated water supply, water quality and health concerns could also be an issue. Factors that influence the potential severity Packet Page 295
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of a full or partial dam failure are the amount of water impounded; the density, type, and value of development and infrastructure located downstream; and the speed of failure.
7.1.2 LEVEE FAILURE
Levees are man-made structures, usually earthen embankments, designed and constructed to contain, control, or divert a flow of water in order to protect land from peak flood levels or to protect land that is below sea level. Levees reinforce the banks of streams and help prevent flooding by containing higher flow events to the channel. By confining the flow to a narrower steam channel, levees can also increase the speed of the water. Levees provide strong flood protection, but they are not failsafe. Levees are designed to protect against a specific flood level and could be overtopped during severe weather events or dam failure. Levees reduce, not eliminate, the risk to individuals and structures located behind them.
A levee breach occurs when part of a levee gives way, creating an opening through which floodwaters may pass. A breach may occur gradually or suddenly. The most dangerous breaches happen quickly during periods of high water. The resulting torrent can quickly swamp a large area behind the failed levee with little or no warning. When a levee system fails or is overtopped, severe flood damage can occur due to increased water surface elevation associated with levees and the resulting increase in water velocity.
Earthen levees can be damaged in several ways. For instance, strong river currents and waves can erode the surface. Trees growing on a levee can blow over, leaving a hole where the root wad and soil used to be. Burrowing animals, such as the California ground squirrel, the salt marsh harvest mouse, or the western burrowing owl can create holes that enable water to pass through a levee. If severe enough, any of these situations can lead to a zone of weakness that could cause a levee breach. In seismically active areas, earthquakes and ground shaking can cause a loss of soil strength, weakening a levee and possibly resulting in failure. Seismic activity can also cause levees to slide or slump, both of which can lead to failure. No levee provides protection from events for which it was not designed, and levees require maintenance to continue to provide the level of protection they were designed and built to offer.
7.1.3 REGULATORY OVERSIGHT
National Dam Safety Act
Potential for catastrophic flooding due to dam failures led to passage of the National Dam Safety Act (Public Law 92-367). The National Dam Safety Program requires a periodic engineering analysis of most dams in the country. The goal of this FEMA-monitored effort is to identify and mitigate the risk of dam failure in order to protect lives and property of the public.
The National Dam Safety Program is a partnership among the states, federal agencies, and other stakeholders that encourages individual and community responsibility for dam safety.
Under FEMA’s leadership, state assistance funds have allowed all participating states to improve their programs through increased inspections, emergency action planning, and Packet Page 296
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purchases of needed equipment. FEMA has also expanded existing and initiated new training programs. Grant assistance from FEMA provides support for improvement of dam safety programs that regulate most of the dams in the United States.
California Division of Safety of Dams
California’s Division of Safety of Dams (DSOD), a division of the Department of Water Resources (DWR), monitors dam safety at the state level. Dams regulated by the DSOD are more than 25 feet in height and hold back more than 15 acre-feet of water or are more than 6 feet in height and hold more than 50 acre-feet of water. DSOD assigns hazard ratings to large dams within the State. Dams are classified in four categories based on the potential hazard to life and property:
• Extremely High Hazard – Expected to cause considerable loss of human life or would result in an inundation area with a population of 1,000 or more. • High Hazard – Expected to cause loss of at least one human life. • Significant Hazard – No probable loss of human life but can cause economic loss, environmental damage, impacts to critical facilities, or other significant impacts. • Low Hazard – No probable loss of human life and low economic and environmental losses. Losses are expected to be principally limited to the owner’s property.
Federal Energy Regulatory Commission Dam Safety Program The Federal Energy Regulatory Commission (FERC) cooperates with many federal and state agencies to ensure and promote dam safety. More than 3,000 dams are part of regulated hydroelectric projects in the FERC program. Two-thirds of these are more than 50 years old. As dams age, concern about their safety and integrity grows, so oversight and regular inspection are important. FERC inspects hydroelectric projects on an unscheduled basis to investigate potential dam safety problems, complaints about constructing and operating a project, safety concerns related to natural disasters, and issues concerning compliance with the terms and conditions of a license.
Every five years, an independent engineer approved by the FERC must inspect and evaluate projects with dams higher than 32.8 feet (10 meters), or with a total storage capacity of more than 2,000 acre-feet. FERC monitors seismic research and applies it in performing structural analyses of hydroelectric projects. FERC also evaluates the effects of potential and actual large floods on the safety of dams. During and following floods, FERC visits dams and licensed projects, determines the extent of damage, if any, and directs any necessary studies or remedial measures the licensee must undertake.
FERC requires licensees to prepare emergency action plans and conducts training sessions on how to develop and test these plans. The plans outline an early warning system if there is an actual or potential sudden release of water from a dam due to failure. The plans include operational procedures that may be used, such as reducing reservoir levels and reducing downstream flows, as well as procedures for notifying affected residents and agencies responsible for emergency management.
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US Army Corps of Engineers Dam Safety Program
The US Army Corps of Engineers is responsible for safety inspections of some federal and nonfederal dams in the US that meet the size and storage limitations specified in the National Dam Safety Act. They have inventoried such dams and surveyed each state and federal agency’s capabilities, practices, and regulations regarding design, construction, operation, and maintenance of the dams.
US Army Corps of Engineers and FEMA Levee Oversight
The Army Corp and FEMA have differing roles and responsibilities related to levees. The Corps addresses operation and maintenance, risk communication, risk management, and risk reduction issues as part of its responsibilities under the Levee Safety Program. FEMA addresses mapping and floodplain management issues related to levees, and it accredits levees as meeting requirements set forth by the National Flood Insurance Program.
Depending on the levee system, the Corps and FEMA may be involved with a levee sponsor and community independently or jointly. The two agencies’ long-term goals are similar: to reduce risk and lessen the devastating consequences of flooding. Army Corps and FEMA partnering activities related to levees include the following:
• Joint meetings with levee sponsors and other stakeholders • Integration of levee information into the National Levee Database • State Silver Jackets teams
• Sharing of levee information
• Targeted task forces to improve program alignment.
Coordination between the Corps and FEMA on levees is now standard within many of each agency’s policies and practices. Over the past several years, both agencies coordinated policies where appropriate; jointly participated in meetings with stakeholders; and participated in many multiagency efforts, such as the National Committee on Levee Safety, the Federal Interagency Floodplain Management Task Force, and the Silver Jackets Program, which brings together state, federal, tribal, and local agencies to learn from each other and apply their knowledge to reduce risk from hazards.
National Committee on Levee Safety
Congress created the National Committee on Levee Safety to develop recommendations for a national levee safety program. The Committee notes that when combined, aging levees, increased development in the floodplain, and increasing frequency of flooding due to climate change, point to an overall increase in the risk of flooding due to levee overtopping or failure.
The Committee seeks to use an integrated approach to creating reliable levee systems and protecting people and property from floods. The Committee is made up of representatives from the Army Corps, FEMA, state, regional, and local agencies, and the private sector and has been working toward this goal since October 2008.
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7.1.4 DAMS IN MONTEREY COUNTY
The following dams are located in or have inundation zones in Monterey County:
Table 7-1: Dams in or Owned by Monterey County
Table 7-1
Dams in or Owned by Monterey County*
Facility
Name
Water
Course Owner Dam Type Downstream Hazard Condition
San Antonio San Antonio
River
Monterey County
Water Resources
Agency
Earthen
Embankment
Extremely
High Fair
Los Padres Carmel
River
California
American Water
Earthen
Embankment
Extremely
High Satisfactory
Pacific Grove Pacific
Ocean
California
American Water
Earthen
Embankment Low Satisfactory
Forest Lake Off stream
Pebble Beach
Community
Services District
Earthen
Embankment
Extremely
High Satisfactory
Black Rock
Creek
Black Rock
Creek Private Earth and Rock Low Satisfactory
Silacci Unnamed Private Earthen
Embankment Significant Fair
Nacimiento1 Nacimiento
River
Monterey County
Water Resources
Agency
Earthen
Embankment
Extremely
High Satisfactory
*Excludes Federally owned Dams
1Located in San Luis Obispo County
Source: Division of Safety of Dams, Dams Within Jurisdiction of the State of California For the purposes of this Plan, the Nacimiento, San Antonio, Forest Lake, and Los Padres dams will be discussed in more detail as they pose an Extremely High downstream hazard and are considered by FEMA as High Hazard Potential Dams (HHPD).
Nacimiento Dam
Nacimiento Dam and its reservoir, the Nacimiento Reservoir, are located in northern San Luis Obispo County, about 20 miles from the coast, in central California. This earth-filled dam was completed in 1957.When the reservoir is full (elevation 800 feet), it has a maximum storage capacity of 377,900 acre-feet, is 18 miles long, and has about 165 miles of shoreline. The maximum elevation during flood stage is 825 feet, with a maximum temporary capacity of 538,000 acre-feet and a temporary surface area of 7,149 acres. Nacimiento Dam is under the jurisdiction of the DWR DSOD and the FERC. The FERC has jurisdiction over the project due to the existence of the hydroelectric plant. Nacimiento Dam was constructed and is owned by the Packet Page 299
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Monterey County Water Resources Agency (MCWRA). It serves as a flood control, water conservation, and recreation facility.
For the purposes of this plan, the following relevant plans, and studies specific to the Nacimiento Dam were reviewed:
• Nacimiento Dam EAP; WRA Rev #3 12/17/2021
• Nacimiento Dam Spillway Condition Assessment Report; GEI 2018 • Nacimiento Dam construction documentation
• Nacimiento Dam periodic inspection reports
• Nacimiento Dam FERC Part 12D Potential Failure Mode Analysis Reports • Nacimiento Dam FERC Part 12D Safety Inspection Reports • Nacimiento Dam Seismic Stability Review Report; GEI 2005 • Nacimiento Dam Safety Surveillance and Monitoring Reports • Probable Maximum Flood Hydrology Report for Nacimiento Reservoir and Supplements; GEI 2001, 2003, and 2004
San Antonio Dam
San Antonio Dam and its reservoir, the San Antonio Reservoir, are located in southern Monterey County, about 16 miles northwest of Paso Robles, in central California. This earthfilled dam was completed in 1967. When the reservoir is full (elevation 780 feet), it has a maximum storage capacity of 335,000 acre-feet, is 16 miles long, and has about 100 miles of shoreline. The maximum elevation during flood stage is 802 feet, with a maximum temporary capacity of about 477,000 acre-feet and a temporary surface area of about 7,500 acres. San Antonio Dam is under the jurisdiction of the DSOD. Like Nacimiento Dam, San Antonio Dam was constructed and is owned by the MCWRA. It serves as a flood control, water conservation, and recreation facility.
For the purposes of this plan, the following relevant plans, and studies specific to the San Antonio Dam were reviewed:
• San Antonio Dam Spillway Condition Assessment Report; GEI 2018 • San Antonio Dam construction documentation
• San Antonio Dam periodic inspection reports
• San Antonio Dam Performance Evaluation Reports
• San Antonio Dam Seismic Analysis Report; Bechtel 1970 • Probable Maximum Flood Hydrology Report for San Antonio Reservoir; GEI 1999 Forest Lake Dam
The Forest Lake Dam, and its reservoir, the Forest Lake Reservoir, is in the Pebble Beach area in the Del Monte Forest. In December 1998, the Pebble Beach Community Services District (PBCSD) purchased the Forest Lake Reservoir from California-American Water Company (CalAm). Following the purchase, the reservoir was rehabilitated, including new improvements to Packet Page 300
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meet the DSOD requirements. During winter months, when there is excess production at the Carmel Area Wastewater District’s treatment plant, the reservoir is filled with recycled water.
Stored recycled water is then used during summer months when the irrigation demands exceed the production, thereby further reducing the use of potable water. The rehabilitation of the reservoir started in 2005 and completed in 2006. In 2009, outlet structure of the reservoir was modified to increase the storage capacity from 105 million gallons to 115 million gallons.
Los Padres Dam
The Los Padres Dam, built in 1949 along the Carmel River, is located 25 miles upstream from the ocean. The dam is a rock and earth-filled dam which is as high as a thirteen-story building; its base is as thick as a football field and has an overall crest measurement of 680 feet. The dam is owned and operated by California-American Water Company (Cal-Am) and serves as a flood control and water conservation facility. The reservoir has a 3,200-acre feet of storage capacity.
The Los Padres Reservoir is steadily filling with sediment, as the pervasively fractured granitic and metamorphic rock underlying the Carmel River watershed is easily eroded.
Sediment loads may greatly increase when fires reduce vegetation cover and are followed by large rainfall events, as occurred after the 1977 Marble Cone Fire that produced catastrophic debris flows. The Monterey Peninsula Water Management District (MPWMD) has undertaken several studies that fully evaluate the various options available for Los Padres Dam. The studies include consideration of dam removal and the development of new location for water storage "off-mainstem" of the Carmel River. This alternative was determined to best meet the longterm needs of water supply, instream flows, and fish passage within the watershed and represented the most effective means of maximizing beneficial use of the basin's available hydrology.
7.1.5 LEVEES IN MONTEREY COUNTY
Monterey County contains about 52 linear miles of levees. Most levees in the County are privately owned agricultural levees. Table 7-2 summarizes levee miles by waterway.
Table 7-2: Miles of Levee in Monterey County by Waterbody Table 7-2
Miles of Levee in Monterey County by Waterbody
Waterbody Miles of Levee
Bennett Slough 0.9
Carmel River 2.1
Elkhorn Slough 5.6
Moro Cojo Slough 4.3
Pajaro River 9.2
Salinas River 29.6
Total 51.7
Source: US Army Corp of Engineers, National Levee Database Packet Page 301
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Pajaro River Levee
The Pajaro River is located in Santa Cruz and Monterey County with the River being the approximate County line. The Pajaro River Levee System was built as a federal flood control project, authorized by Section 10 of the Flood Control Act of December 1944. The Army Corps of Engineers designed and constructed the levees and associated system components within the Pajaro River Basin in the late 1940s. The project was built to reduce flood risk to the City of Watsonville, the town of Pajaro and surrounding areas by reducing flooding over the channel banks. The project primarily consists of earthen levees, with a low flow channel. The low flow channel varies in elevation but is typically about 25 feet below the levee crest elevation.
The left (southern) bank of the Pajaro Levee system is located in Monterey County and extends from the Pacific Ocean to Murphy Road. The town of Pajaro is located behind the left bank levee. The levee maintenance agency for the left bank is the MCWRA. MCWRA has an emergency plan that identifies critical stages of the river and the related actions that the Office of Emergency Services takes such as declaring an emergency and mobilizing emergency responders. The MCWRA also has an ALERT system that monitors river levels whenever significant storms approach the area.
The right (northern) bank of the Pajaro River Levee system is owned/operated by the Santa Cruz County Flood Control and Water Conservation District – Zone 7. Santa Cruz County, Zone 7, and the City of Watsonville have an Emergency Action Plan. The County can monitor stream gages and when a critical water level is reached, alert the public through a reverse 911 system.
The County also has an evacuation plan that covers a range of disasters and an ALERT Storm System.
Carmel River Levees
Levees have been constructed by private interests on the Carmel River from State Highway 1 upstream approximately 4,000 feet on the north bank, and from 3,000 feet upstream of the mouth to 10,000 feet upstream of the mouth on the south bank. These levees are not adequate to hold the 100-year flood.
7.2 HAZARD PROFILE
7.2.1 HISTORY
Dam Failure
There is no record of any damages, fatalities, or injuries associated with dam failure in the Monterey County. However, water has been released over the Nacimiento Dam spillway crest five times (1958, 1969, 1983, 2011, and 2017) over the last 63 years, and the San Antonio Dam spillway crest three times (1982, 1983, and 2006) over the past 55 years.
The state’s most recent dam emergency occurred in February 2017 when the Oroville Dam in Butte County was on the verge of overflow. The dam’s concrete spillway was damaged by erosion and a massive hole developed. The auxiliary spillway was used to prevent overtopping Packet Page 302
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of the dam, and it experienced erosion problems
also. Evacuation orders were issued in advance of a
potential large uncontrolled release of water from
Lake Oroville, but such a release did not occur.
After this incident, state officials ordered that the
flood-control spillways of 93 dams be re-inspected
for potential geologic, structural, or performance
issues that could jeopardize their ability to safely
pass a flood event.
Levee Failure
In March 1995, a 10–20-year storm event, caused a
breach in the Pajaro levee approximately 3 miles
upstream of the town of Pajaro. The drainage
system in the flat town could not adequately
discharge the stormwater runoff in the streets. This
resulted in mass evacuations and damage to private
property. All residences (600+) and businesses in
Pajaro were damaged and 2,500 people were
evacuated.
Several locations along the Pajaro Levee were
damaged and had to be repaired after the 1989
Loma Prieta earthquake causing damage to roads
and property. An atmospheric river event in
January of 2017 caused a levee breach along the
Carmel River near Paso Hondo in Carmel Valley
Village, impacting 20 to 30 homes.
7.2.2 LOCATION
Dam Failure
A dam failure is possible at any dam in Monterey
County. The most likely location of a damaging
levee failure would be at dams classified as having
extremely high downstream hazard, which as
previously mentioned includes the Nacimiento, San
Antonio, Forest Lake, and Los Padres Dams.
The Nacimiento, San Antonio, and Los Padres Dams
are older and are the most likely locations of a dam
failure.
Mitigation Success Story
San Clemente Dam Removal
The San Clemente Dam was a large concrete
dam located about 18 miles from the Ocean
on the Carmel River. Over time the reservoir
became increasingly sedimented and no
longer served as a water source. The dam
posed a safety concern and could have failed
in the event of a large earthquake or flood.
Due to safety and environmental concerns,
the CA Coastal Conservancy, NOAA, and
California American Water decided to reroute the river and remove the dam. As of 2019, the Carmel River is returning to its wild
state and the fish population is rebounding.
At the time, this was the largest dam removal
project in California history.
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All three dams and reservoirs are inspected annually by the DSOD to ensure that they are in good operating condition. Nacimiento receives an additional annual inspection from FERC. Both Nacimiento and San Antonio receive periodic inspections by Water Resource Agency staff.
These dam safety programs reduce risk associated with the dams but do not eliminate the possibility of a dam failure. During the winter, temporary flood storage is provided in flood pools in Nacimiento and San Antonio reservoirs.
Along the Los Padres Dams, excess water can be released through transmission pipes, valves, and spillway systems. However, use of the dam spillways for flood control releases would most likely occur during severe winter storms, when the dams and reservoirs are receiving increased inflow. Damage from a dam failure is most likely to occur in mapped dam failure inundation zones. Shown in Figure 7-1 is the dam failure inundation zones for a spillway or full dam failure at the Nacimiento Dam.
Figure 7-1
Nacimiento Dam Failure Inundation Zone
Figure 7-1: Nacimiento Dam Failure Inundation Zone
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As of April 2019, the San Antonio Dam spillway has been identified to have significant foundation and structural deficiencies such that the spillway is in poor condition and unsafe for use under high flow conditions. Major rehabilitation or full replacement of the spillway will be needed to ensure the safe performance of the spillway under significant flows up to the maximum design outflow. The California Department of Water Resources, Division of Safety of Dams requires the San Antonio dam spillway be restored to full function by November 1, 2024.
Shown in Figure 7-2 is the dam failure inundation zones for a spillway or full dam failure at the San Antonio Dam.
Figure 7-2
San Antonio Dam Failure Inundation Zone Figure 7-2: San Antonio Dam Failure Inundation Zone The inundation zones for both the Los Padres Dam and the Forest Lake Dam are mapped in Figure 7-3.
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Figure 7-3
Los Padres and Forest Lake Dam Failure Inundation Zones Figure 7-3: Los Padres and Forest Lake Dam Failure Inundation Zones Levee Failure
A levee failure is possible along any levee in Monterey County. The most likely location of a damaging levee failure would be at the Carmel River Levees, the Pajaro River Levee, or at one of the many levees along the Salinas River.
For the NFIP, FEMA only recognizes levee systems that meet minimum design, operation, and maintenance standards. Therefore, there is a possibility that unaccredited levees exist in Monterey County, which do not meet FEMA standards and that could be a location of a levee failure. Since information is not available on the locations of such levees, risk associated with unaccredited levees is beyond the scope of this plan.
Levee miles and leveed area in Monterey County is shown in Figure 7-4.
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Figure 7-4
Levees in Monterey County
Figure 7-4: Levees in Monterey County
7.2.3 FREQUENCY
Dam Failure
Dam failure events are infrequent and usually coincide with events that cause them, such as earthquakes, landslides, and excessive rainfall and snowmelt. Although the recent Oroville event raised public concern about dam failure, the probability of such failures remains low in today’s regulatory environment.
All dams face a “residual risk” of failure, which represents the risk that conditions may exceed those for which the dam was designed. For example, dams may be designed to withstand a probable maximum precipitation, defined as the theoretically, greatest depth of precipitation for a given duration that is physically possible over a given storm area at a particular geographical location at a certain time of the year. The chance of occurrence of a precipitation event of a greater magnitude than that represents residual risk for such dams. This in turn represents a theoretical probability of future occurrence for a dam failure event, though the Packet Page 307
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probability of an event exceeding the assumed maximum is not generally calculated as part of dam design.
Levee Failure
Levee failure probabilities are considered to be higher than dam failure probabilities because levees are often exposed to more adverse conditions associated with high velocity flood flows, such as erosion and scour. Many levees are designed to overtop in high flow conditions; such overtopping is referred to as design failure.
7.2.4 SEVERITY
Dam Failure
Dam failure can be catastrophic to all life and property downstream. The US Army Corps of Engineers developed the classification system shown in Table 7-3 for the hazard potential of dam failures.
Table 7-3: US Army Corps of Engineers Dam Hazard Potential Classification Table 7-3
US Army Corps of Engineers Dam Hazard Potential Classification Hazard
Category Direct Loss of Life Lifeline & Property Losses Environmental Losses Low None expected
No disruption of services; Loss of
isolated buildings, agricultural
lands, and equipment
Minimal incremental
damage
Significant None expected
Disruption of essential facilities and
access; major loss of public and
private facilities
Major mitigation
required
High Probable. One or
more expected
Disruption of essential facilities and
access; Extensive loss of public and
private facilities
Extensive or
impossible to mitigate
The Army Corps has classified the Forest Lake, Los Padres, San Antonio, and Nacimiento Dams as High Hazard29 Dam inundation maps show that the greatest risk from dam failure is in Carmel Valley, where failure of the Los Padres would cause inundation of urbanized areas and alter the riparian corridor. Dam failure in Salinas Valley would also be significant, whether caused by the failure of San Antonio or Nacimiento Reservoir. Studies reveal that either failure would overflow the 100-year floodplain in Salinas Valley. However, the risk would predominately be to agricultural land.
Levee Failure
In the event of a levee failure, floodwaters may ultimately inundate the protected area landward of the levee. The extent of inundation is dependent on the flooding intensity. Failure of a levee during a 1% annual chance flood will inundate the 100-year floodplain previously 29 US Army Corp of Engineers, National Inventory of Dams Packet Page 308
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protected by the levee. Residential and commercial buildings nearest the levee overtopping or breach location will suffer the most damage from the initial embankment failure flood wave.
Landward buildings will be damaged by inundation.
One major risk for the Pajaro River levee is of a breach before water flows over the levee (overtopping). This breach is associated with seepage (water leaking through the levee) and resulting erosion of the levee slope. The other major risk is from overtopping (water flowing over the levee) which also results in levee erosion and the potential for a breach. If a breach occurs, water could flood the town of Pajaro and surrounding agricultural lands rapidly, leading to significant economic damage and potential loss of life. While these conditions are possible, they are not certain to take place during a flood event. The past evacuations and flood events have increased community awareness and reduced the likelihood for life loss through the implementation of the notification and evacuation plans.
7.2.5 WARNING T IME
Dam Failure
Warning time for dam failure varies depending on the cause of the failure, the size of the dam and volume of water retained, and the location of the dam. In events of extreme precipitation or massive snowmelt, evacuations can be planned with sufficient time. In the event of a structural failure due to earthquake, there may be no warning time. A dam’s structural type also affects warning time. All dams of concern in Monterey County are earthen dams, which do not tend to fail completely or instantaneously. Once a breach is initiated, discharging water erodes the breach until either the reservoir water is depleted, or the breach resists further erosion. The time of breach formation ranges from a few minutes to a few hours.
The number of people to be alerted and evacuated in the event of impending dam failure can vary widely. A major factor to consider is the initial flow in the river when the failure occurs.
The initial flow is normally very low on all the rivers between May and October. During the winter, the initial flow is much higher. This wide variation in initial flow has a significant impact on the areas that must be evacuated.
Levee Failure
Warning time for levee failures depends on the cause of the failure. A levee failure caused by structural failure can be sudden and occur with little to no warning. If heavy rains are impacting a levee system, communities located in the immediate danger zone can be evacuated before a failure occurs. If the levee failure is caused by overtopping, the community may or may not be able to recognize the impending failure and evacuate. If a levee failure occurs suddenly, evacuation may not be possible.
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7.3 SECONDARY HAZARDS
Dam and levee failure can cause severe downstream flooding, depending on the magnitude of the failure. Other potential secondary hazards are landslides, bank erosion, and destruction of downstream habitat. Levee failures can also cause environmental incidents due to hazardous materials releases when floodwaters infiltrate facilities that store these types of materials.
Additionally, dam failure may worsen the severity of a drought by releasing water that might have been used as a potable water source. A failure of the Nacimiento or San Antonio dam could affect water availability for downstream agricultural users. If the dams were to fail or otherwise be unable to provide regular water releases, it would affect the ability of growers to exercise their right to those surface waters for supplementing recycled water and could cause a corresponding increase in groundwater usage.
7.4 RISK ASSESSMENT
For the purposes of this risk assessment, dam failure risk was assessed for the dams that are classified as High Hazard by the Army Corps of Engineers, which includes the Nacimiento, San Antonio, Forest Lake, and Los Padres Dams. Inundation zone data for the Nacimiento and San Antonio dams were provided by MCWRA. Inundation data for the Forest Lake Dam were provided by the Pebble Beach Community Services District. Inundation data for the Los Padres Dam were from the DWR DSOD California Dam Inundation Map data.
Data on levee location, leveed area, and population and property exposed to levee failure risk were from the US Army Corp of Engineers, National Levee Database. Leveed Area, which is defined as the estimated area of a floodplain from which flood water is excluded by the levee system, was used to determine the population and property exposed to levee failure.
7.4.1 POPULATION
Dam Failure
All residents in a dam failure inundation zone would be exposed to the risk of a dam failure.
Population exposed to a failure of the Nacimiento Dam is summarized in Table 7-4.
Table 7-4: Population Exposed to Dam Failure- Nacimiento Dam Table 7-4
Population Exposed to Dam Failure in Monterey County- Nacimiento Dam Supervisorial District Spillway Failure Dam Failure
District 1 0 0
District 2 4,391 6,876
District 3 3,779 7,427
District 4 1,493 11,372
District 5 2,690 3,091
Total 12,353 28,766
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Population exposed to a failure of the San Antonio Dam is summarized in Table 7-5.
Table 7-5: Population Exposed to Dam Failure- San Antonio Dam Table 7-5
Population Exposed to Dam Failure in Monterey County- San Antonio Dam Supervisorial District Spillway Failure Dam Failure
District 1 0 0
District 2 2,509 5,757
District 3 1,024 7,742
District 4 174 9,318
District 5 66 3,090
Total 3,773 25,907
A failure of the Los Padres Dam would impact a population of 5,784, all located in Monterey County Supervisorial District 5, in the Carmel Valley area.
Population exposed to a failure of the Forest Lake Dam is summarized in Table 7-6. Impacts are not summarized by Supervisorial District, as all impacts would occur in Monterey County Supervisorial District 5 in the Pebble Beach community.
Table 7-6: Population Exposed to Dam Failure- Forest Lake Dam Table 7-6
Population Exposed to Dam Failure in Monterey County- Forest Lake Dam Scenario Population
Scenario 1- North Embankment Failure 302
Scenario 2- South Embankment Failure 403
Scenario 3- Outlet Structure Failure 23
Scenario 4- NW End of South Embankment Failure 834
The potential for loss of life is affected by the capacity and number of evacuation routes available to those living in potential inundation areas. Vulnerable populations are all populations downstream from dam failures that are incapable of escaping the area within the allowable time frame. This population includes the elderly and young who may be unable to get themselves out of the inundation area.
The vulnerable population also includes those who would not have adequate warning from a television or radio emergency warning system.
Levee Failure
Those living in an area protected by a levee would be exposed to levee failure risk in the event of a levee failure event.
Table 7-7 summarizes population exposed to levee failure risk by water body in Monterey County.
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Table 7-7: Population Exposed to Levee Failure by Waterbody Table 7-7
Population Exposed to Levee Failure in Monterey County by Waterbody Waterbody Miles of Levee Population
Bennett Slough 0.9 6
Carmel River 2.1 633
Elkhorn Slough 5.6 0
Moro Cojo Slough 4.3 0
Pajaro River 9.2 3,597
Salinas River 29.6 23
Total 51.7 4,259
Source: US Army Corp of Engineers, National Levee Database A failure of the left (southern) bank of the Pajaro levee would threaten the population of the town of Pajaro, which includes a population of 2,700 to 3,600 people who are located within the floodplain with the higher number of populations at night. There is also potential for loss of life from levee breaching.
Similar to dam failure, vulnerable populations are all populations in a leveed area that are incapable of escaping the area within the allowable time frame. This population includes the elderly and young who may be unable to get themselves out of the inundation area. The vulnerable population also includes those who would not have adequate warning from a television or radio emergency warning system. Homeless encampments are sometimes located along levees and those populations would be immediately vulnerable if a levee were to fail.
7.4.2 PROPERTY
Dam Failure
All property in a dam failure inundation zone would be exposed to the risk of a dam failure.
Residential property exposed to a failure of the Nacimiento Dam is summarized by failure type in Table 7-8. Non-residential property exposed to a failure of the Nacimiento Dam is summarized by failure type in Table 7-9.
Table 7-8: Residential Property Exposed to Dam Failure- Nacimiento Dam Table 7-8
Residential Property Exposed to Dam Failure in Monterey County- Nacimiento Dam Supervisorial
District
Spillway Failure Dam Failure
# Value # Value
District 1 0 $0 0 $0
District 2 102 $64,518,030 547 $215,959,574
District 3 350 $111,015,165 930 $296,389,365
District 4 18 $7,953,691 2,449 $1,085,984,861
District 5 18 $6,264,905 201 $119,647,543
Total 488 $189,751,791 4,127 $1,717,981,343
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Table 7-9: Non-Residential Property Exposed to Dam Failure- Nacimiento Dam Table 7-9
Non-Residential Property Exposed to Dam Failure in Monterey County- Nacimiento Dam Supervisorial
District
Spillway Failure Dam Failure
# Value # Value
District 1 0 $0 0 $0
District 2 1,573 $284,272,763 1,739 $359,562,190
District 3 601 $1,046,736,191 1,237 $1,913,669,147
District 4 212 $318,310,350 1,081 $652,433,746
District 5 81 $75,470,973 149 $97,208,521
Total 2,467 $1,724,790,277 4,206 $3,022,873,604
Residential and non-residential property exposed to a failure of the San Antonio Dam is summarized by failure type in Table 7-10 and Table 7-11, respectively.
Table 7-10: Residential Property Exposed to Dam Failure- San Antonio Dam Table 7-10
Residential Property Exposed to Dam Failure in Monterey County- San Antonio Dam Supervisorial
District
Spillway Failure Dam Failure
# Value # Value
District 1 0 $0 0 $0
District 2 25 $14,955,579 356 $160,541,542
District 3 27 $3,896,226 862 $290,548,892
District 4 6 $1,878,279 1,829 $817,783,466
District 5 5 $1,925,278 270 $158,562,338
Total 63 $22,655,362 3,317 $1,427,436,238
Table 7-11: Non-Residential Property Exposed to Dam Failure- San Antonio Table 7-11
Non-Residential Property Exposed to Dam Failure in Monterey County- San Antonio Dam Supervisorial
District
Spillway Failure Dam Failure
# Value # Value
District 1 0 $0 121 $81,861,626
District 2 1,365 $163,566,067 1,709 $344,429,789
District 3 458 $708,840,660 1,226 $1,603,644,752
District 4 84 $156,648,583 883 $570,421,330
District 5 47 $60,066,878 164 $99,018,359
Total 1,954 $1,089,122,188 4,103 $2,699,375,856
A failure of the Los Padres Dam would impact 943 residential properties, valued at $779,795,548 and 419 non-residential properties, valued at $196,382,343. All impacted property would be in Monterey County Supervisorial District 5, in the Carmel Valley area.
Residential property exposed to a failure of the Forest Lake Dam by failure type is summarized in Table 7-12. Non-residential property exposed to a failure of the Forest Lake Dam by failure Packet Page 313
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type is summarized in Table 7-13. Impacts are not summarized by Supervisorial District, as all impacts would occur in Supervisorial District 5 in the Pebble Beach community.
Table 7-12: Residential Property Exposed to Dam Failure- Forest Lake Dam Table 7-12
Residential Property Exposed to Dam Failure in Monterey County- Forest Lake Dam Scenario Number Value
Scenario 1- North Embankment Failure 38 $47,663,347
Scenario 2- South Embankment Failure 48 $54,833,015
Scenario 3- Outlet Structure Failure 0 $0
Scenario 4- NW End of South Embankment Failure 266 $356,389,582 Table 7-13: Non-Residential Property Exposed to Dam Failure- Forest Lake Dam Table 7-13
Non-Residential Property Exposed to Dam Failure in Monterey County- Forest Lake Dam Scenario Number Value
Scenario 1- North Embankment Failure 12 $97,873,581
Scenario 2- South Embankment Failure 16 $62,584,773
Scenario 3- Outlet Structure Failure 0 $0
Scenario 4- NW End of South Embankment Failure 52 $77,207,153 Vulnerable properties are those closest to the dam inundation area. These properties would experience the largest, most destructive surge of water. Low-lying areas are also vulnerable since they are near where the dam waters would collect. Properties in the dam inundation zone that are built to NFIP minimum construction standards may have some level of protection against dam inundation, depending on the velocity and elevation of the inundation waters.
These properties also are more likely to have flood insurance.
Levee Failure
Any property in an area protected by a levee would be exposed to levee failure risk in the event of a levee failure event. Table 7-14 summarizes land area behind levees, as well as structures and property value exposed to levee failure risk by water body in Monterey County.
Table 7-14: Property Exposed to Levee Failure by Waterbody Table 7-14
Property Exposed to Levee Failure in Monterey County by Waterbody Waterbody Miles of Levee Leveed Area in
Square Miles Structures Property Value
Bennett Slough 0.9 0.35 1 $544,000
Carmel River 2.1 0.17 111 $258,000,000
Elkhorn Slough 5.6 0.62 0 $0
Moro Cojo Slough 4.3 0.87 0 $0
Pajaro River 9.2 5.97 811 $481,000,000
Salinas River 29.6 8.51 8 $55,501,000
Total 51.7 16.49 931 $795,045,000
Source: US Army Corp of Engineers, National Levee Database Packet Page 314
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The southern bank of the Pajaro levee reduces flood risk for agricultural areas and the town of Pajaro which sits within the floodplain. There is potential for high economic damages if a levee breach occurs and 800 structures at risk of flooding. While not all land protected by levee is agricultural, much of the 16.49 square miles of the land protected by levees in Monterey County is likely agricultural. Therefore, a levee failure could threaten important agricultural value.
7.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
Dam Failure
Transportation routes have the potential to be destroyed due to dam failure. This includes all roads, railroads, and bridges in the path of the dam inundation. Notably, Highway 101 would be at risk if the Nacimiento or San Antonio Dam were to fail. Carmel Valley Road would be at risk due to a failure of the Los Padres Dam.
Transportation routes vulnerable to dam inundation have the potential to be wiped out and could create isolation issues. Those that are most vulnerable are those that are already in poor condition and would not be able to withstand a large water surge.
Utilities such as overhead power lines, cable and phone lines could also be at risk if any dam were to fail. Loss of these utilities could create additional isolation issues for the inundation areas. Table 7-15 summarizes critical infrastructure identified as vulnerable to dam failure risk.
Table 7-15: Critical Infrastructure Exposed to Dam Failure Risk Table 7-15
Critical Infrastructure Exposed to Dam Failure Risk in Monterey County Critical Infrastructure
Type
Nacimiento San Antonio Forest Lake
(Scenarios) Los
Dam Padres
Failure
Spillway
Failure
Dam
Failure
Spillway
Failure 1 2 3 4
Facilities
Emergency Response 4 0 1 0 0 0 0 0 0
Fire Station 3 0 1 0 0 0 0 0 1
Police Station 2 0 2 0 0 0 0 0 0
Medical Facilities 4 0 4 0 0 0 0 0 2
Military Facility 0 0 0 0 0 0 0 0 0
Large Public Facility 0 0 0 0 0 0 0 0 0
Educational Facilities 12 0 6 0 0 0 0 0 1
Power Plant 1 0 1 0 0 0 0 0 0
Water & Wastewater 32 14 28 2 0 0 0 0 21
Stormwater Facilities 9 5 7 0 0 0 0 0 0
Government Facilities 14 2 12 0 0 0 0 0 1
Communication Facilities 80 24 64 9 2 2 2 2 6
Rain Gauges 9 3 7 3 0 0 0 0 1
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Table 7-15
Critical Infrastructure Exposed to Dam Failure Risk in Monterey County Critical Infrastructure
Type
Nacimiento San Antonio Forest Lake
(Scenarios) Los
Dam Padres
Failure
Spillway
Failure
Dam
Failure
Spillway
Failure 1 2 3 4
Hazardous Materials
Active or Idle Oil Well 1,050 811 955 100 0 0 0 0 0
Landfill 0 0 0 0 0 0 0 0 0
Underground Tank 6 1 3 0 0 0 0 0 0
Cal ARP Facility 8 3 7 0 0 0 0 0 1
Transportation
Airport 1 0 0 0 0 0 0 0 0
Bridge 28 21 26 11 0 0 0 0 7
Harbor 1 1 1 1 0 0 0 0 0
Highway (Miles) 96 42 63 8 0 0 0 0 0
Major Road (Miles) 109 38 111 15 0 0 0 0 0.7
Local Road (Miles) 159 57 133 10 3 2 0 4 25
Railroad (Miles) 45 11 46 2 0 0 0 0 0
Levee Failure
A failure of the left bank of the Pajaro levee could threaten critical infrastructure in the town of Pajaro, which includes a middle school, PG&E distribution lines, and industrial sites.
7.4.4 ENVIRONMENT
The environment would be exposed to a number of risks in the event of dam failure or levee failure event. The inundation could introduce many foreign elements into local waterways. This could result in destruction of downstream habitat and could have detrimental effects on many species of animals, especially endangered species such as steelhead.
7.4.5 ECONOMIC IMPACT
Dam and levee failure would likely impact Monterey County’s agricultural economy. When a dam fails or a levee is breached, soil and crop damages in the flooded bottomland areas that impact agricultural management capacities and crop productivity. Breached levees appreciably impact freshwater resources, damage crops and livestock, destroy homes, schools, businesses, and wild species habitat, among other vital, sensitive areas. Levee failure often leads to oil and petroleum contamination of freshwater resources, particularly in dense residential, agricultural, and commercial areas protected by levee systems that depend upon such water resources for drinking, irrigation, and industrial uses.
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7.5 FUTURE TRENDS IN DEVELOPMENT
Most of the areas vulnerable to the more severe impacts from dam and levee failure intersect the mapped flood hazard areas. Flood-related policies in the general plans of participating jurisdictions will help to reduce the risk associated with dam and levee failure for all future development. Flooding due to a dam or levee failure could exceed the special flood hazard areas regulated through local floodplain ordinances, and therefore the County and participating jurisdictions should still consider this hazard when permitting development in mapped dam inundation zones and downstream of high hazard and significant hazard dams. Low hazard dams could become significant or high hazard dams if development occurs below them.
7.6 ISSUES
The most significant issue associated with dam and levee failure involves the properties and populations in the inundation zones. Flooding as a result of a dam or levee failure would significantly impact these areas. There is often limited warning time for dam or levee failures.
These events are frequently associated with other natural hazard events such as earthquakes, landslides, or severe weather, which limits their predictability and compounds the hazard.
Important issues associated with dam and levee failure hazards include the following:
• Dam and levee infrastructure may require repair and improvement to withstand climate change impacts.
• Federally regulated dams have an adequate level of oversight and sophistication in the development of emergency action plans for public notification in the unlikely event of failure. However, the protocol for notification of downstream citizens of imminent failure needs to be tied to local emergency response planning. • Mapping for federally regulated dams is already required and available; however, mapping for nonfederal-regulated dams that estimates inundation depths is needed to better assess the risk associated with dam failure from these facilities. • Most dam failure mapping required at federal levels requires determination of the probable maximum flood. While the probable maximum flood represents a worst-case scenario, it is generally the event with the lowest probability of occurrence. For nonfederal-regulated dams, mapping of dam failure scenarios that are less extreme than the probable maximum flood but have a higher probability of occurrence can be valuable to emergency managers and community officials downstream of these facilities. This type of mapping can illustrate areas potentially impacted by more frequent events to support emergency response and preparedness. • The concept of residual risk associated with structural flood control projects should be considered in the design of capital projects and the application of land use regulations. • Addressing security concerns and the need to inform the public of the risk associated with dam failure is a challenge for public officials.
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8. DROUGHT
8.1 OVERVIEW
Drought is a significant decrease in water supply relative to what is typical in a given location. It is a normal phase in the climate cycle of most regions, originating from a deficiency of precipitation over an extended period of time, usually a season or more. This leads to a water shortage for some activity, group, or environmental sector. High temperatures, high winds, and low humidity can worsen drought conditions, and can make areas more susceptible to wildfire.
Human demands and actions can also hasten drought-related impacts.
Droughts are frequently classified as one of the four types: meteorological, agricultural, hydrological, or socioeconomic. Meteorological droughts are typically defined by the level of “dryness” when compared to an average, or normal amount of precipitation over a given period of time. Agricultural droughts relate common characteristics of drought to their specific agricultural-related impacts (when the amount of moisture in soil does not meet the needs of a particular crop). Hydrological drought is directly related to the effect of precipitation shortfalls on surface and groundwater supplies. Human factors, particularly changes in land use, can alter the hydrologic characteristics of a basin. Socioeconomic drought is the result of water shortages that affect people and limit the ability to supply water-dependent products in the marketplace.
Droughts cause public health and safety impacts, as well as economic and environmental impacts. Public health and safety impacts are primarily associated with catastrophic wildfire risks and drinking water shortage risks for small water systems in rural areas and private residential wells. Drought impacts are felt first by people most dependent on annual rainfall – Packet Page 319
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such as ranchers using dryland range or rural residents relying on wells in low-yield rock formations.
Drought impacts increase with the length of a drought, as carry-over supplies in reservoirs are depleted and water levels in groundwater basins decline. At times, drought may also cause community-wide impacts because of acute water shortages (regulatory use restrictions, drinking water supply, and seawater intrusion). The magnitude of such impact’s correlates directly with local groundwater supplies, reservoir storage, and development densities. Drought conditions can also contribute to or exacerbate extreme heat concerns, particularly with regard to elderly populations.
8.1.1 DROUGHT IN CALIFORNIA
Most of California’s precipitation comes from storms moving across the Pacific Ocean. The path followed by the storms is determined by the position of an atmospheric high-pressure belt that normally shifts southward during the winter, allowing low pressure systems to move into the State. On average, 75% of California’s annual precipitation occurs between November and March, with 50% occurring between December and February. A persistent Pacific high-pressure zone over California in mid-winter signals a tendency for a dry water year.
A typical water year produces about 100 inches of rainfall over the North Coast, 50 inches of precipitation (combination of rain and snow) over the Northern Sierra, 18 inches in the Sacramento area, and 13 inches to 23 inches in the planning area. In extremely dry years, these annual totals can fall to as little as one half, or even one third of these amounts. The Sierra Nevada snowpack serves as the primary agent for replenishing water in the San Francisco Bay area, including Monterey County, and for much of the State of California. A reduction in spring snowpack runoff, whether due to drier winters or to increasing temperatures leading to more rain than snow, can increase risk of summer or fall water shortages throughout the region.
8.1.2 DROUGHT CONDITIONS
The US Drought Monitor (USDM) uses a five-category system to label the severity of droughts.
Drought categories show experts’ assessments of conditions related to dryness and drought including observations of how much water is available in streams, lakes, and soils compared to usual for the same time of year. Drought is classified into five categories:
Since no two states experience the same set of impacts
during a drought. USDM has developed tables of impacts
reported during past droughts in each state for each level of drought on the US Drought Monitor. Impacts by drought
category for California are listed in Table 8-1.
D0 - Abnormally Dry
D1 - Moderate Drought
D2 - Severe Drought
D3 - Extreme Drought
D4 - Exceptional Drought
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Table 8-1: Drought Impacts by USDM Drought Category in California Table 8-1
Drought Impacts by USDM Drought Category in California
D0
Soil is dry; irrigation delivery begins early; Dryland crop germination is stunted Active fire season begins
Winter resort visitation is low; snowpack is minimal
D1
Dryland pasture growth is stunted; producers give supplemental feed to cattle Landscaping and gardens need irrigation earlier; wildlife patterns begin to change Stock ponds and creeks are lower than usual
D2
Grazing land is inadequate; Trees are stressed; plants increase reproductive mechanisms; wildlife diseases increase
Producers increase water efficiency methods and drought-resistant crops Fire season is longer, with high burn intensity, dry fuels, and large fire spatial extent; more fire crews are on staff
Wine country tourism increases; lake- and river-based tourism declines Water temperature increases, programs to divert water to protect fish begin River flows decrease; reservoir levels are low, and banks are exposed D3
Livestock need expensive supplemental feed, cattle and horses are sold; little pasture remains; Orchard removal and well drilling company business increase Fruit trees bud early; producers begin irrigating in the winter Federal water is not adequate to meet irrigation contracts; extracting supplemental groundwater is expensive
Fire season lasts year-round; fires occur in wet parts of state; burn bans implemented Low river levels impede fish migration and cause lower survival rates Wildlife encroaches on developed areas; little native food and water is available for bears, which hibernate less
Water sanitation is a concern, reservoir levels drop significantly, surface water is nearly dry, flows are exceptionally low; water theft occurs Wells and aquifer levels decrease; homeowners drill new wells Water conservation rebate programs increase; water use restrictions are implemented; water transfers increase
Water is inadequate for agriculture, wildlife, and urban needs; reservoirs are extremely low; hydropower is restricted
D4
Fields are left fallow; orchards are removed; vegetable yields are low Fire season is very costly; number of fires and area burned are extensive Fish rescue begins; forest mortality is high; wetlands dry up; survival of native plants and animals is low; wildlife death is widespread; algae blooms appear Policy change, agriculture unemployment is high, food aid is needed Poor air quality affects health, greenhouse gas emissions increase as hydropower production decreases; West Nile Virus outbreaks rise
Water shortages are widespread; surface water is depleted; federal irrigation water deliveries are extremely low; junior water rights are curtailed; water quality is poor Water prices are extremely high; wells are dry, more, and deeper wells are drilled Packet Page 321
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8.1.3 LOCAL WATER SUPPLY AND WATER SHORTAGE
Monterey County is isolated from State and Federal water supplies and must rely solely on its local water resources, historically, groundwater and surface water from watersheds with negligible influence from snowpack. The Monterey County Water Resources Agency manages two large reservoirs: San Antonio and Nacimiento. The Monterey Peninsula depends on two water sources: the Carmel River, which drains a 255-square-mile watershed and runs 36 miles from its source in the Santa Lucia mountains to the sea; and the Seaside Basin, which is recharged by local rain, and which underlies the City of Seaside as well as parts of the former Fort Ord and Highway 68 corridor.
Groundwater is the major source of water for many water users in more rural areas of Monterey County with the exception of residents along the Big Sur coast, who depend entirely on surface water and shallow wells for their water supply, and of residents in an area near Greenfield in the Salinas Valley, who have a diversion from the Arroyo Seco River.
High demands on water resources during severe drought can limit water supply. During critically dry years, the California State Water Resources Control Board can mandate water conservation by water users and agencies to address statewide water shortages. Table 8-2 lists State Drought Management Program stages mandated to water right holders.
Table 8-2: State Drought Management Program
Table 8-2
State Drought Management Program
Drought
Stage
State Mandated Customer
Demand Reduction Rate Impacts
Stage 0 or 1 <10% Normal rates
Stage 2 10 to 15% Normal rates; Drought surcharge
Stage 3 15 to 20% Normal rates; Drought surcharge
Stage 4 >20% Normal rates, Drought surcharge
Several efforts are also underway to provide recycled water and reduce the risk seawater intrusion. The Pure Water Monterey Groundwater Replenishment Project (PWM/GWR) replenishes the Seaside Basin with an average of 3500 acre-feet/year of advanced purified recycled water which is injected to the Basin via a series of shallow and deep injection wells.
The recycled water mixes with native groundwater and is stored for later potable water supply.
The Salinas Valley Reclamation Project (SVRP) provides recycled water to growers in the Salinas Valley. The distribution portion of the system, known as the Castroville Seawater Intrusion Project (CISP), delivers water through 45 miles of pipeline to 12,000 acres of farmland in the northern Salinas Valley nearly year-round. While SVRP does not produce potable water, it does help agricultural users in the CSIP area reduce their reliance on the 180- and 400-foot aquifers, which are the source of potable water supply for several communities including Castroville and the City of Salinas.
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8.2 HAZARD PROFILE
8.2.1 HISTORY
The California Department of Water Resources has state hydrologic data back to the early 1900s. The hydrologic data show multi-year droughts from 1912 to 1913, 1918 to 1920, 1922 to 1924, and 1928 to 1934. Since then, a number of prolonged periods of drought occurred in California, all of which impacted Monterey County to some degree. 1976 to 1977 Drought: California had one of its most severe droughts due to lack of rainfall during the winters of 1976 and 1977. 1977 was the driest period on record in California, with the previous winter recorded as the fourth driest in California’s hydrological history. The cumulative impact led to widespread water shortages and severe water conservation measures throughout the state. Only 37% of the average Sacramento Valley runoff was received, with just
6.6 million acre-feet recorded. Over $2.6 billion in crop damage was recorded in 31 counties.
FEMA declared a drought emergency (Declaration 3023-EM) on January 20, 1977, for 58 California counties.
1987 to 1992 Drought: California received precipitation well below average levels for four consecutive years. While the Central Coast was most affected, the Sierra Nevadas in Northern California and the Central Valley counties were also affected. During this drought, only 56% of average runoff for the Sacramento Valley was received, totaling just 10 million acre-feet. In 1991, the State Water Project sharply decreased deliveries to water suppliers. By February 1991, all 58 counties in California were experiencing drought conditions. Urban areas as well as agricultural areas were impacted.
2007 to 2009 Drought: The governor issued an executive order that proclaimed a statewide drought emergency on June 4, 2008, after spring 2008 was the driest spring on record, with low snowmelt runoff. On February 27, 2009, the governor proclaimed a state of emergency for the entire state as severe drought conditions continued. The largest court-ordered water restriction in state history (at the time) was imposed.
2012 to 2016 Drought: The most recent major drought in California set several records for the state and was one of the most severe droughts on record. On January 17, 2014, Governor Jerry Brown declared a statewide drought emergency in response to California’s driest year on record, with nearly 99% of the state considered abnormally dry or worse, and almost two-thirds of the state (including Monterey County) in extreme drought conditions. In the State of Emergency declaration, Governor Brown directed state officials to assist farmers and communities that are economically impacted by dry conditions. The Governor also directed state agencies to use less water and hire more firefighters and initiated a greatly expanded water conservation public awareness campaign. On April 2, 2017, Governor Brown lifted the drought emergency, but declared that California must continue water conservation efforts.
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2021 Drought: On July 8, 2021, Governor Gavin Newsom declared a drought emergency in Monterey County along with 8 other Counties. This declaration was an expansion of the May 10, 2021, drought declaration, with 50 of California's 58 counties now included in the drought emergency declaration. Drought conditions in California as of August 17, 2021, are shown in Figure 8-1.
Figure 8-1
US Drought Monitor, Drought Conditions as of August 17, 2021 Figure 8-1: US Drought Monitor, Drought Conditions as of August 17, 2021 Source: The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. Map courtesy of NDMC.
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The US Department of Agriculture (USDA) declares agriculture-related disasters for losses resulting from drought, flood, fire, freeze, tornadoes, pest infestation, and other natural disasters. Between 2012 and 2021, the period for which data was available, Monterey County was included in 21 USDA disaster declaration in relation to drought, listed in Table 8-3.
Table 8-3: USDA Agricultural Disaster Designations in Monterey County (2012-2021) Table 8-3
USDA Agricultural Disaster Designations in Monterey County (2012-2021) Designation
Number Disaster Type Crop Disaster Year
S4958 Drought 2021
S4969 Drought 2021
S4916 Drought 2021
S4467 Drought 2019
S4460 Drought 2018
S4144 Drought 2017
S4163 Drought 2017
S3952 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2016 S3784 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2015 S3943 Drought 2015
S3626 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2014 S3637 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2014 S3626 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2014 S3637 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2014 S3743 Drought 2014
S3491 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2013 S3497 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2013 S3504 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2013 S3547 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2013 S3569 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2013 S3268 Drought, High Winds, Wildfire, Excessive Heat, and Insects 2012 S3379 Drought 2012
S3452 Drought 2012
Source: United States Department of Agriculture (USDA), Disaster Designation Information, Last updated August 20, 2021 The National Drought Mitigation Center developed the Drought Impact Reporter in response to the need for a national drought impact database for the US. Information comes from a variety of sources: on-line, drought-related news stories and scientific publications, members of the public, members of the media, and staff of government agencies.
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The Drought Impact Reporter found that Monterey County was affected by 111 impacts from droughts from January 2012 through November 2021 in the following categories (note that some impacts have been assigned to more than one category). 30
8.2.2 LOCATION
Drought is a regional phenomenon with the potential to impact the entire population of Monterey County directly or indirectly, be it from water restrictions, higher water and food prices, reduced air or water quality, or restricted access to recreational areas. No portion of the County is immune from drought conditions. However, the most significant financial losses are likely to occur in areas that are primarily agricultural.
Lack of winter snowfall in the mountains can eventually lead to agricultural impacts due to decreased stream flows. Droughts of just a few weeks during critical periods of plant development can have disastrous effects on agriculture production. Reduced reservoir storage from decreased runoff in the mountains can lead to water shortages. Droughts that occur in populated areas may not have direct effects to the residents but may increase the threat of wildfire in the wildland urban interface areas.
8.2.3 FREQUENCY
Droughts originate from a deficiency of precipitation resulting from an unusual weather pattern. If the weather pattern lasts a short time (a few weeks or a couple of months), the drought is considered short-term. If the weather pattern becomes entrenched and the 30 Drought Impact Reporter, National Drought Mitigation Center 59 Relief, Response & Restrictions Impacts
57 Water Supply & Quality Impacts
35 Agriculture Impacts
31 Society & Public Health Impacts
22 Plants & Wildlife Impacts
19 Fire Impacts
7 Tourism & Recreation Impacts
6 Business & Industry Impacts
5 Energy Impacts
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precipitation deficits last for several months or years, the drought is considered to be longterm. It is possible for a region to experience a long-term circulation pattern that produces drought, and to have short-term changes in this long-term pattern that result in short-term wet spells. Likewise, it is possible for a long-term wet circulation pattern to be interrupted by shortterm weather spells that result in short-term drought.
According to historical data prepared by the National Drought Mitigation Center, Monterey County, has experienced some level of drought almost every year during the past 20 years.
Time series data by percentage area in drought conditions in Monterey County from the US Drought Monitor 31 is shown in Figure 8-2. Therefore, droughts likely are likely to occur frequently in Monterey County at varied severities in the future.
Figure 8-2
Monterey County Percentage Area Drought Conditions
Figure 8-2: Monterey County Percentage Area Drought Conditions
8.2.4 SEVERITY
Drought can have a widespread impact on the environment and the economy, although it typically does not result in loss of life or damage to property. The severity of a drought depends on the degree of moisture deficiency, the duration, and the size and location of the affected area. The longer the duration of the drought and the larger the area impacted, the more severe the potential impacts. Unlike most disasters, droughts normally occur slowly but last a long time. Drought can have severe impacts in Monterey County’s water resources, which are already over-stretched by the demands of a growing agriculture economy and population.
The agricultural sector clearly demonstrates the site-specific nature of drought impacts.
Agricultural drought impacts are normally felt earliest by those relying on unmanaged water supplies: entities carrying out dryland grazing and non-irrigated crop production, usually grain crops. Impacts to irrigated agriculture depend on the source and nature of the irrigation water supply, whether it be local groundwater, local surface water, or imported surface water, and 31 Time Series Data, US Drought Monitor
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any water rights or contractual provisions that may be associated with the source. The extent to which producers may mitigate water shortage impacts depends on multiple factors but is heavily influenced by economic considerations. Factors involved in making decisions about mitigating irrigation water shortages include availability and costs of pumping groundwater, price of alternative surface water sources, capital investments associated with maintaining permanent plantings, and status of international crop markets.
Drought generally does not affect groundwater sources as quickly as surface water supplies, but groundwater supplies generally take longer to recover. Reduced precipitation during a drought means that groundwater supplies are not replenished at a normal rate, and in many cases, groundwater is more heavily relied upon during periods of drought due to a reduction in surface water availability. This can lead to a reduction in groundwater levels, decreases in water quality, and problems such as reduced pumping capacity or wells going dry. Long term drought conditions in the County could lead to increased groundwater mining in the Deep Aquifers.
Reduced replenishment of groundwater also affects streams. Much of the flow in streams comes from groundwater, especially during the summer when there is less precipitation and after snowmelt ends. Reduced groundwater levels mean that even less water will enter streams when steam flows are lowest.
8.2.5 WARNING TIME
Droughts are climatic patterns that occur over long periods of time. Only generalized warning can take place due to the numerous variables that scientists have not pieced together well enough to make accurate and precise predictions. Empirical studies conducted over the past century have shown that meteorological drought is never the result of a single cause. It is the result of many causes, often synergistic in nature; these include global weather patterns that produce persistent, upper-level high-pressure systems along the West Coast with warm, dry air resulting in less precipitation.
Scientists currently do not know how to predict drought more than a month in advance for most locations. Predicting drought depends on the ability to forecast precipitation and temperature. Anomalies of precipitation and temperature may last from several months to several decades. How long a drought will last depends on interactions between the atmosphere and the oceans, soil moisture and land surface processes, topography, internal dynamics, and the accumulated influence of weather systems on the global scale.
8.3 SECONDARY HAZARDS
Drought is often accompanied by extreme heat, exposing people to the risk of sunstroke, heat cramps and heat exhaustion. Pets and livestock are also vulnerable to heat-related injuries.
Crops can be vulnerable as well. For more information on heat risk in Monterey County, refer to Severe Weather in Section 14.
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8.3.1 SEAWATER INTRUSION
Droughts can cause and exacerbate seawater intrusion in Monterey Bay area. Drought conditions can lead to increases in groundwater pumping, including potential pumping from deep aquifers, and this loss of groundwater increases seawater intrusion. According to the 2015 Urban Water Management Plan for the Salinas District, the annual non-drought overdraft of the Salinas Valley Groundwater Basin is estimated to be approximately 45,300 AF per year. During droughts, the annual overdraft can escalate to between 150,000 to 300,000 AF per year. As a result of this consistent overdraft, groundwater levels in the Salinas Valley Groundwater Basin have dropped below sea level, allowing seawater to intrude from Monterey Bay into aquifers located 180 and 400 feet below ground surface. While basin overdraft conditions are expected to improve by the year 2030 due to water reclamation efforts, recent groundwater modeling from the Salinas Valley Integrated Ground and Surface Water Model (SVIGSM) predicted seawater intrusion to continue to worsen, though at a decreased rate.
8.3.2 WILDFIRE
A prolonged lack of precipitation dries out vegetation, which becomes increasingly susceptible to wildfire ignition as the duration of the drought extends. For more information on wildfire risk in Monterey County, refer to Wildfire in Section 18.
8.3.3 DEBRIS FLOWS
Post-fire vegetation recovery on burn scars is necessary for winter-storm slope stability.
Drought conditions may slow the vegetation recovery rates on burn scars causing a higher debris flow likelihood for a longer period following a wildfire. For more information on debris flow risk in Monterey County, refer to Slope Failure in Section 15.
8.4 RISK ASSESSMENT
The National Drought Mitigation Center uses three categories to describe likely drought impacts:
• Population/Social Impacts: These impacts affect people’s health and safety. Social impacts include public safety, health, conflicts between people when there is not enough water to go around, and changes in lifestyle.
• Economic Impacts: These impacts of drought cost people (or businesses) money, farmers’ crops are destroyed; low water supply necessitates spending on irrigation or to drill new wells; businesses that sell boats and fishing equipment may not be able to sell their goods.
• Environmental Impacts: Plants and animals depend on water. When a drought occurs, their food supply can shrink, and their habitat can be damaged.
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8.4.1 POPULATION AND SOCIAL IMPACTS
The entire population of Monterey County is vulnerable to drought events. Drought can affect people’s health and safety, including health problems related to low water flows, poor water quality, or dust. Drought also is often accompanied by extreme heat, exposing people to the risk of sunstroke, heat cramps and heat exhaustion. Other possible impacts include recreational risks; effects on air quality; diminished living conditions related to energy, air quality, and hygiene; compromised food and nutrition; and increased incidence of illness and disease.
Water shortages can affect access to safe, affordable water, with substantial impacts on lowincome families and communities burdened with environmental pollution. Disadvantaged communities in areas in the Central Coast region, such as the City of Salinas, were highly affected by water shortages during the 2011-2016 drought and another extend period of drought would likely disproportionality affect low-income communities. Drought changes also exacerbated affordability concerns for low-income households
8.4.2 ECONOMIC IMPACT
Drought causes the most significant economic impacts on industries that use water or depend on water for their business, most notably, agriculture and related sectors (forestry, fisheries, and waterborne activities), power plants and oil refineries. In addition to losses in yields in crop and livestock production, drought is associated with increased insect infestations, plant diseases, and wind erosion. Drought can lead to other losses because so many sectors are affected- losses that include reduced income for farmers and reduced business for retailers and others who provide goods and services to farmers. This leads to unemployment, increased credit risk for financial institutions, capital shortfalls, and loss of tax revenue. Prices for food, energy, and other products may also increase as supplies decrease. Although most businesses will still be operational, they may be affected aesthetically—especially the recreation and tourism industry. Moreover, droughts within another area could affect food supply/price of food for residents within the County.
Monterey County’s agricultural sector is particularly vulnerable to drought conditions, with consequences that directly relate to the water available for irrigation purposes. Heat conditions associated with drought exacerbate agricultural irrigation demands when water levels are at their lowest. Reduction in precipitation coupled with heat stress can adversely impact crop production. In the Salinas Valley, agricultural water is made available from groundwater sources that are recharged by the Salinas River, which relies on water releases from the Nacimiento, and San Antonio reservoirs as controlled by MCWRA. Since 1990, growers in the Castroville Seawater Intrusion Project (CSIP) distribution system area have utilized tertiary-treated recycled water produced by M1W in partnership with MCWRA to irrigate their crops. In 2006, M1W and MCWRA added the Salinas River Diversion Facility (SRDF), which supplies recycled water to 12,000 acres of productive farmland. The SRDF relies upon water from the upstream Reservoirs to operate, providing Salinas River flows to supplement recycled water and further Packet Page 330
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reduce groundwater pumping in the 180- and 400-foot aquifers of the Salinas Valley Groundwater Basin. During years when the SRDF is non-operational due to drought, a corresponding increase in groundwater pumping in CSIP region has been observed.
8.4.3 ENVIRONMENTAL IMPACT
Environmental losses from drought are associated with damage to plants, animals, wildlife habitat, and air and water quality; forest and range fires; degradation of landscape quality; loss of biodiversity; and soil erosion. Some of the effects are short-term and conditions quickly return to normal following the end of the drought. Other environmental effects linger for some time or may even become permanent. Wildlife habitat, for example, may be degraded through the loss of wetlands, lakes, and vegetation. However, many species will eventually recover from this temporary aberration. The degradation of landscape quality, including increased soil erosion, may lead to a more permanent loss of biological productivity. Although environmental losses are difficult to quantify, growing public awareness and concern for environmental quality has forced public officials to focus greater attention and resources on these effects.
8.5 FUTURE TRENDS IN DEVELOPMENT
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 to deal with issues of water supply and protection of water resources. These plans increase capability at the local municipal level to protect future development from impacts of drought. All planning partners reviewed their general plans under the capability assessments undertaken for this hazard mitigation plan. Deficiencies revealed by these reviews are identified as mitigation actions to increase capability to deal with future trends in development.
8.6 ISSUES
• The probability of increased drought frequencies and durations due to climate change. • The promotion of active water conservation even during non-drought periods. • Application of alternative techniques (groundwater recharge, continued/expanded water reclamation, local capture and reuse, desalination, and transfer) to stabilize and offset water supply shortfalls.
• Regular occurrence of drought or multiyear droughts that may limit the County’s ability to successfully recover from or prepare for more occurrences. • The impact of prolonged drought conditions on Monterey County’s agricultural industry, a key economic driver in the County.
• Severe drought could have serious impacts on water quality. • Increased groundwater pumping during drought years exacerbating seawater intrusion. • A severe drought would result in drier fuels which could create increased wildfire risk.
Lack of water due to drought could also impede firefighting capabilities.
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9. EARTHQUAKE
9.1 OVERVIEW
An earthquake is a sudden motion or trembling caused by an abrupt shift of rock along a fracture in the earth or a contact zone between tectonic plates. Most destructive quakes are caused by dislocations of the crust. The crust may first bend and then, when the stress exceeds the strength of the rocks, break, and snap to a new position. In the process of breaking, vibrations called “seismic waves” are generated. These waves travel outward from the source of the earthquake at varying speeds. Earthquakes usually occur without warning and, after just a few seconds, can cause massive structural damage, injury, and loss of life, as well as damage to infrastructure networks, such as water, power, gas, communication, and transportation. The effects of an earthquake can be felt far beyond the site of its occurrence. The degree of damage depends on many interrelated factors. Among these are: the magnitude, focal depth, distance from the causative fault, source mechanism, duration of shaking, high rock accelerations, type of surface deposits or bedrock, degree of consolidation of surface deposits, presence of high groundwater, topography, and the design, type, and quality of building construction.
9.1.1 EARTHQUAKE GEOLOGY
The Earth’s crust, which is the rigid outermost shell of the planet, is broken into seven or eight major tectonic plates and many minor plates. Where the plates meet, they move in one of three ways: convergent (two plates moving together), divergent (two plates moving apart), or transform (two plates moving parallel to one another). Earthquakes, volcanic activity, mountain building, and oceanic trench formation occur along plate boundaries.
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Subduction is a geological process that takes place at convergent boundaries of tectonic plate, in which one plate moves under another. Regions where this process occurs are known as subduction zones, and they have the potential to generate highly damaging earthquakes. The transform (parallel) movement of tectonic plates against one another creates stresses that build as the rocks are gradually deformed. The rock deformation, or strain, is stored in the rocks as elastic strain energy. When the strength of the rock is exceeded, rupture occurs along a fault.
The rocks on opposite sides of the fault slide past each other as they spring back into a more relaxed position. The strain energy is released partly as heat and partly as elastic waves called seismic waves. The passage of seismic waves produces the ground shaking in earthquakes.
Monterey County lies within the California Coast Ranges, a region dominated by active tectonic movement of the North American Plate, east of the San Andreas Fault, and the Pacific Plate to the west. Regional tectonic forces generate an estimated relative motion between the North American and Pacific plates of approximately 2 inches per year. Over time, these forces have created the varied mountainous, valley, and fault-bound blocks seen in the County today.
Geologists have found that earthquakes tend to reoccur along faults, which are zones of weakness in the earth’s crust. Even if a fault zone has recently experienced an earthquake, there is no guarantee that all stress has been relieved. Another earthquake could still occur. In fact, relieving stress along one part of a fault may increase it in another part. Therefore, faults are mapped to determine earthquake hazards. In California, a system has been developed by the California Geological Survey (CGS) and US Geological Survey (USGS) to assess the activity of faults. CGS categorizes faults based on the age of last displacement, as defined below:
• Historic faults have ruptured during historic time (approximately the last 200 years) and are associated with either a recorded earthquake with surface rupture, measurable surface displacement along a fault in the absence of notable earthquakes (e.g., aseismic creep), or displaced survey lines.
• Holocene age faults have ruptured within the past 11,000 years, as demonstrated by geomorphic or stratigraphic evidence of displacement of Holocene deposits or geomorphic features.
• Late Quaternary age faults have ruptured within approximately the last 700,000 years, as demonstrated by geologic and geomorphic evidence of displacement of Late Quaternary deposits or geomorphic features. This category may include younger faults that lack deposits by which to differentiate younger displacements. • Quaternary age faults show evidence of surface rupture younger than approximately 1.6 million years ago.
• Pre-Quaternary age faults lack recognized evidence of Quaternary displacement or show evidence of no displacement during Quaternary time. Also included in this category are known faults for which detailed studies have not determined fault activity, and those faults identified only in preliminary mapping.
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The classification of “active” is applied to historic and Holocene age faults; “potentially active” is applied to Quaternary and late Quaternary age faults; and “inactive” is applied to preQuaternary age faults. These classifications are not meant to imply that inactive faults will not rupture, only that they have not been shown to have ruptured for some time and the probability of fault rupture is low. Known faults in the County by age are shown in Figure 9-1.
Figure 9-1
Known Faults in Monterey County by Age
Figure 9-1: Known Faults in Monterey County by Age
9.1.2 EARTHQUAKE CLASSIFICATIONS
Earthquakes are typically classified in one of two ways: By the amount of energy released, measured as magnitude; or by the impact on people and structures, measured as intensity.
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Magnitude
The most common method for measuring earthquakes is magnitude, which measures the strength of earthquakes. An earthquake’s magnitude is a measure of the energy released at the source of the earthquake and is related to the total area of the fault that ruptured, the amount of displacement across the fault, and the actual location of the energy release inside the earth.
The Richter scale measures magnitude of earthquakes based on the amplitude of the largest energy wave released by the earthquake. Richter scale readings are suitable for smaller earthquakes; however, because it is a logarithmic scale, the scale does not clearly distinguish the magnitude of large earthquakes above a certain level.
Therefore, while the Richter scale is the most well-known measurement for earthquake magnitude, the majority of scientists currently use the Moment Magnitude (Mw) Scale to measure magnitude. As shown in Table 9-1, there are seven earthquake magnitude classes, ranging from great to micro. A magnitude class of great can cause tremendous damage to infrastructure, compared to a micro class, which results in minor damage to infrastructure.
Table 9-1: Earthquake Magnitude Classes (Moment Magnitude Scale) Table 9-1
Earthquake Magnitude Classes (Moment Magnitude Scale)
Magnitude Class Magnitude Range Description
Great Magnitude > 8 Tremendous Damage
Major 7 ≤ Magnitude < 7.9 Widespread Heavy Damage
Strong 6 ≤ Magnitude < 6.9 Severe Damage
Moderate 5 ≤ Magnitude < 5.9 Considerable Damage
Light 4 ≤ Magnitude < 4.9 Moderate Damage
Minor 3 ≤ Magnitude < 3.9 Rarely Causes Damage
Micro Magnitude < 3 Minor Damage
Intensity
Although an earthquake has only one magnitude, it can have many intensities. The effects of an earthquake in a particular location are measured by intensity. Intensity at a given site is a function of earthquake magnitude, increasing as magnitude increases; distance from the causative fault, decreasing as distance increases; and underlying site geology, generally increasing in areas with weak, unconsolidated materials. Earthquake intensity decreases with increasing distance from the epicenter of the earthquake.
The Modified Mercalli Intensity value assigned to a specific site after an earthquake is a more meaningful measure of severity to the nonscientist than magnitude because intensity refers to the effects experienced at that place. The lower numbers on the intensity scale generally deal with the how the earthquake is felt by people, while the higher numbers are based on observed structural damage.
Table 9-2 provides an overview of the Modified Mercalli Intensity scale.
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Table 9-2: Modified Mercalli Intensity Level Descriptions Table 9-2
Modified Mercalli Intensity Level Descriptions
Intensity Shaking Description/ Damage
I Not Felt Not felt except by a very few under especially favorable conditions.
II Weak Felt by only a few persons at rest, especially on upper floors of building. Delicately suspended objects may swing.
III Weak
Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake.
Standing motor cars may rock slightly. Vibrations similar to the passing of a truck. Duration estimated.
IV Light
Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.
V Moderate
Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.
Disturbances of trees, poles, and other tall objects sometimes noticed.
VI Strong
Felt by all, many frightened. Many objects fall from shelves. Some heavy furniture moved; a few instances of fallen plaster, broken windows, and damaged chimneys. Damage slight. Some fall of tree limbs, isolated rockfalls and landslides, and isolated liquefaction.
VII Very
Strong
Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. Tree damage, rockfalls, landslides, and liquefaction are more severe and widespread with increasing intensity.
VIII Severe
Many find it difficult to stand. Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse; great in poorly built structures. Panel walls thrown out of frame structures. Fall of chimneys, factory stacks, columns, monument walls, and heavy furniture overturned. Sand and mud ejected in small amounts. Changes in well water. Persons driving in cars disturbed.
IX Violent
Some forcibly thrown to the ground. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. Ground cracked conspicuously. Underground pipes broken.
X Extreme
Some well-built structures destroyed; most masonry and frame structures destroyed with foundations; ground badly cracked.
Railway lines bent. Landslides considerable from riverbanks and steep slopes. Shifted sand and mud.
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9.1.3 GROUND MOTION
Earthquake hazard assessment is also based on expected ground motion. The ground experiences acceleration as it shakes during an earthquake. The peak ground acceleration (PGA) is the largest acceleration recorded by a monitoring station during an earthquake. PGA is a measure of how hard the earth shakes in a given geographic area and is expressed as a percentage of the acceleration due to gravity. Horizontal and vertical PGA varies with soil or rock type. Instruments called accelerographs record levels of ground motion due to earthquakes at stations throughout a region. These readings are recorded by state and federal agencies that monitor and predict seismic activity. Earthquake hazard assessment involves estimating the annual probability that certain ground motion accelerations will be exceeded, and then summing the annual probabilities over a time period of interest.
Maps of earthquake shaking hazards provide information for creating and updating seismic design requirements for building codes, insurance rate structures, earthquake loss studies, retrofit priorities and land use planning. After thorough review of the studies, professional organizations of engineers update the seismic-risk maps and seismic design requirements contained in building codes.
Building codes that include seismic provisions specify the horizontal force due to lateral acceleration that a building should be able to withstand during an earthquake. Buildings, bridges, highways, and utilities built to meet modern seismic design requirements are typically able to withstand earthquakes better, with less damage and disruption. PGA values are directly related to these lateral forces that could damage “short period structures” such as single-family dwellings. Longer-period response components determine the lateral forces that damage larger structures with longer natural periods such as apartment buildings, factories, high-rises, and bridges. Table 9-3 lists damage potential and perceived shaking by PGA factors, compared to the Mercalli scale.
Table 9-3: Modified Mercalli Scale and Peak Ground Acceleration Table 9-3
Modified Mercalli Scale and Peak Ground Acceleration
Modified
Mercalli Scale
Perceived
Shaking
Potential Structural Damage Estimated PGA
Resistant Buildings Vulnerable Buildings (%g)
I Not Felt None None < 0.17%
II-III Weak None None 0.17% - 1.4%
IV Light None None 1.4% - 3.9%
V Moderate Very Light Light 3.9% - 9.2%
VI Strong Light Moderate 9.2% - 18%
VII Very Strong Moderate Moderate/Heavy 18% - 34%
VIII Severe Moderate/Heavy Heavy 34% - 65%
IX Violent Heavy Very Heavy 65% - 124%
X - XII Extreme Very Heavy Very Heavy > 124%
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9.1.4 LIQUEFACTION
The impact of an earthquake on structures is a function of ground shaking, distance from the source of the quake, and liquefaction, an effect of an earthquake in which soils lose their shear strength and behave as liquid, damaging structures that derive their support from the soil.
Liquefaction involves loose sandy soil with a high-water content that undermines the ground’s ability to solidly support building structures during an earthquake. Liquefaction occurs when ground shaking causes the mechanical properties of some fine grained, saturated soils to liquefy and act as a fluid (liquefaction). It is the result of a sudden loss of soil strength due to a rapid increase in soil pore water pressures caused by ground shaking. In order for liquefaction to occur, three general geotechnical characteristics should be present:
• Ground water should be present within the potentially liquefiable zone • The potentially liquefiable zone should be granular and meet a specific range in grainsize distribution • The potentially liquefiable zone should be of low relative density. If those criteria are present and strong ground motion occurs, then those soils could liquefy, depending upon the intensity and duration of the strong ground motion.
Liquefaction that produces surface effects generally occurs in the upper 40 to 50 feet of the soil column, although the phenomenon can occur deeper than 100 feet. The duration of ground shaking is also an important factor in causing liquefaction to occur. The larger the earthquake magnitude, and the longer the duration of strong ground shaking, the greater the potential there is for liquefaction to occur.
A program called the National Earthquake Hazard Reduction Program (NEHRP) creates maps based on soil characteristics to help identify locations subject to liquefaction. Table 9-4 summarizes NEHRP soil classifications. NEHRP Soils B and C typically can sustain ground shaking without much effect, dependent on the earthquake magnitude. The areas that are commonly most affected by ground shaking have NEHRP Soils D, E and F. In general, these areas are also most susceptible to liquefaction.
Table 9-4: NEHRP Soil Classification System
Table 9-4
NEHRP Soil Classification System
NEHRP
Soil Type Description Mean Shear Velocity to 30 m (m/s) A Hard Rock 1,500
B Firm to Hard Rock 760-1,500
C Dense Soil/ Soft Rock 360-760
D Stiff Soil 180-360
E Soft Clays <180
F Special Study Soils- liquefiable soils, sensitive clays, organic soils, soft clays >36 m thick
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9.2 HAZARD PROFILE
9.2.1 HISTORY
Earthquakes tend to reoccur where they have struck before. The central California coast has a history of damaging earthquakes, primarily associated with the San Andreas fault, which runs through the southeastern portion of the County for about 30 miles. There have also been a number of 5.0 to 6.5 earthquakes on other faults which have affected large portions of the region. The County has experienced 429 earthquakes since 1900 and 67 earthquakes since 2000 of 4.0 magnitude or higher. Table 9-5 summarizes the year, epicenter, and magnitude of major earthquakes (6.0 magnitude or more) that have affected the County since 1850.
Table 9-5: Monterey County Earthquakes, Magnitude 6.0+ (1838-Present) Table 9-5
Monterey County Earthquakes, Magnitude 6.0+ (1838-Present) Date Magnitude Location
2004 6.0 Parkfield
2003 6.5 San Simenon
1989 6.9 Loma Prieta
1984 6.1 Morgan Hill
1983 6.5 Coalinga
1952 6.2 Monterey Bay
1966 6.6 Parkfield
1934 6.0 Parkfield
1926 6.3 Monterey Bay
1922 6.5 Parkfield
1906 7.8 San Francisco
1901 6.4 Parkfield
1857 7.9 Parkfield
The approximate 7.9 Fort Tejon earthquake of 1857 was one of the largest earthquakes ever recorded in the US and the largest in California history. It originated in Parkfield in Monterey County and caused a surface rupture scar of about 225 miles in length along the San Andreas Fault to the Cajon Pass northwest of San Bernardino. Yet, despite the immense scale of this quake, only two people were reported killed by the effects of the shock. The fact that only two lives were lost was primarily due to the fact that in 1857 California was sparsely populated, especially in the regions of strongest shaking. Were the Fort Tejon shock to happen today, the damage would easily run into the billions of dollars, and the loss of life would likely be substantial.
In 1906, the 7.8. magnitude San Francisco Earthquake caused severe damage. The Salinas River bottom lands were severely ruptured, fissured, and otherwise deformed. The Spreckels Sugar Mill, situated on the banks of the river, suffered more severely probably than any other steel Packet Page 340
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structure in the State. Other damage from the 1906 earthquake included destruction of the wharf at Moss Landing and destruction of the Hotel Del Monte in Monterey.
On October 17, 1989, the Loma Prieta earthquake occurred in neighboring Santa Cruz County.
The earthquake lasted only 10 to 15 seconds but was a 6.9 magnitude. In Moss Landing, liquefaction destroyed a causeway, damaged the bridge linking the Moss Landing spit to the mainland and cracked the paved road on Paul's Island. 32 A section of Highway 1 through Monterey, a bridge carrying Highway 1 over the Salinas River, and the Salinas River rail bridge suffered damage. In the Old Town Salinas historical district, unreinforced masonry buildings were partially destroyed. The 2004 6.0 magnitude Parkfield earthquake caused only minor damage but was long-anticipated event on the San Andreas fault and is the world’s best recorded earthquake to date.
9.2.2 LOCATION
Monterey County is located in a region of high seismicity with numerous local faults, as shown below. The primary seismic hazard for the County is potential ground shaking from these faults.
Major faults in Monterey County are described below and mapped by slip rate in Figure 9-2.
San Andreas Fault
The San Andreas Fault runs through the southeastern portion of the County for approximately 30 miles and poses the single greatest seismic hazard to the County. To the north and south of the County, the fault appears to be currently locked with no detectable movement. Between these locked sections, within the County, the San Andreas Fault creeps (slips aseismically).
From San Juan Bautista to Parkfield, the creeping section produces numerous small to moderate (mostly magnitude 6.0 and smaller) earthquakes but no large ones. The stretch of the fault between Parkfield and Gold Hill defines a transition zone between the creeping and locked behavior of the fault. The slip rate of the San Andreas fault is Greater than 5.0 mm/year.
Palo Colorado-San Gregorio Fault
The Palo Colorado-San Gregorio Fault zone connects the Palo Colorado Fault near Point Sur, south of Monterey, with the San Gregorio Fault near Point Ano Nuevo in Santa Cruz County. It is a right-lateral strike-slip fault zone oriented generally north-south consisting of two or more parallel and fairly continuous fault segments that extend at least 60 miles. The slip rate of the San Gregorio–Palo Colorado fault is between 1.0 and 5.0 mm/year.
Monterey Bay-Tularcitos Fault
The Monterey Bay-Tularcitos Fault zone lies seaward of the city of Seaside, extending northwesterly to the Pacific Ocean. It is composed of short, discontinuous parallel fault segments ranging from 3 to 9 miles in length.
32 USGS
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The Monterey Bay Fault–Tularcitos zone is either truncated or merges with the San Gregorio fault segment of the Palo Colorado–San Gregorio Fault zone. The slip rate of the Monterey BayTularcitos fault is between 0.2 and 1.0 mm/year.
Figure 9-2
Known Faults in Monterey County by Slip Rate
Figure 9-2: Known Faults in Monterey County by Slip Rate NEHRP Soil Maps
NEHRP soil types define the locations that will be significantly impacted by an earthquake.
Table 9-4 summarizes NEHRP soil classifications. NEHRP Soils B and C typically can sustain lowmagnitude ground shaking without much effect. The areas that are most commonly affected by ground shaking have NEHRP Soils D, E and F.
As shown in Figure 9-3, based on soil type, the location of the most extreme earthquake damage in Monterey County would likely be in some areas of the Monterey Peninsula, areas along the Monterey Bay, and in the Salinas Valley. These areas generally include the largest population centers in the County, and therefore are areas of high concern for earthquake risk reduction.
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Figure 9-3
NEHRP Soil Classes in Monterey County
Figure 9-3: NEHRP Soil Classes in Monterey County
9.2.3 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 California State Hazard Mitigation Plan, earthquakes large enough to cause moderate damage to structures—those of Magnitude 5.5 or larger—occur three to four times a year statewide. Strong earthquakes of Magnitude 6 to 6.9 strike on an average of once every two to three years. Major earthquakes of Magnitude 7 to 7.9 occur in California about once every 10 years. According to the USGS, in the next 30 years, California has a 99.7% chance of a magnitude 6.7 or larger earthquake Geologic studies show that over the past 1,400 to 1,500 years large earthquakes have occurred at about 150-year intervals on the southern segment of the San Andreas Fault (south of Parkfield). As the last large earthquake on the southern San Andreas Fault segment occurred in 1857, that section of the fault is considered a likely location for an earthquake within the next few decades. The northern segment of the fault (north of San Juan Baustista) has a slightly Packet Page 343
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lower potential for a great earthquake, as only about 100 years have passed since the 1906 earthquake. The USGS estimates there is a 72% probability (or likelihood) of at least one earthquake of magnitude 6.7 or greater striking somewhere in the greater San Francisco Bay region before 2043. 33 The 30-year probability of an M ≥ 6.7 earthquake on the northern segment of the San Andreas Fault is 21%.
The San Gregorio–Palo Colorado Fault zone has a 10% probability of a magnitude 6.7 or greater earthquake by 2032. The Calaveras-Paicines Fault, which does not run directly through Monterey County, could also be the location of a major earthquake, which would affect the County. The probability of experiencing a Magnitude 6.7 or greater earthquake along the Calaveras Fault in the next 30 years is 26%.
However, as noted above, Monterey County experiences several small detectable earthquakes every year. Also, moderate-sized, potentially damaging earthquakes could occur in this area at any time.
9.2.4 SEVERITY
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. 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 instrument.
The impact of an earthquake is largely a function of the following components:
• Ground shaking (ground motion accelerations)
• Liquefaction (soil instability)
• Distance from the source (both horizontally and vertically) USGS ground motion maps, based on current information about fault zones, show the PGA that has a certain probability of being exceeded in a 50-year period. Mapping of ground shaking potential was used to assess the risk of earthquakes. the hazard from ground shaking is most severe in areas near the San Andreas Fault and in the unconsolidated alluvial areas of the County such as the Salinas and Carmel Valleys.
Earthquake shaking potential in Monterey County is shown in Figure 9-4. 33 USGS, Earthquake Outlook for the San Francisco Bay Region 2014–2043 Packet Page 344
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Figure 9-4: Earthquake Shaking Potential
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Liquefaction Susceptibility
Soil liquefaction maps are also 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.
Areas in Monterey County most susceptible to liquefaction include the Salinas River and floodplain, the Moss Landing and Elkhorn Slough areas, the Carmel River and floodplain, the San Antonio and Lockwood Valleys, and the Peachtree and Cholame Valleys.
Liquefaction susceptibility in Monterey County is shown in Figure 9-5.
Figure 9-5
Liquefaction Susceptibility in Monterey County
Figure 9-5: Liquefaction Susceptibility in Monterey County Packet Page 346
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9.2.5 WARNING TIME
There is no current reliable way to predict the day or month that an earthquake will occur at any given location. Research is being done with warning systems that use the low energy waves that precede major earthquakes. These potential warning systems give approximately 40 seconds notice that a major earthquake is about to occur. The warning time is very short, but it could allow for someone to get under a desk, step away from a hazardous material they are working with, or shut down a computer system.
In 2019, the USGS released ShakeAlert, an earthquake early warning (EEW) system that detects significant earthquakes quickly so that alerts can reach many people before shaking arrives.
ShakeAlert is not earthquake prediction, rather a ShakeAlert Message indicates that an earthquake has begun, and shaking is imminent. The USGS has estimated the warning time would range from seconds to tens of seconds. ShakeAlert can give enough time to take preventative actions before the shaking starts to reduce damage and casualties during an earthquake. Figure 9-6 provides more information on how the ShakeAlert system works.
Figure 9-6
ShakeAlert Earthquake Early Warning Basics
Figure 9-6: ShakeAlert Earthquake Early Warning Basics
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9.3 SECONDARY HAZARDS
Earthquakes can cause collateral emergencies including dam and levee failures, seiches, hazmat incidents, urban conflagration, avalanches, and landslides. In addition to ground motion, several secondary natural hazards can occur from earthquakes. Additionally, urban conflagration 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.
9.3.1 DAM AND LEVEE FAILURE
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.
For more information on dam and levee failure risk in Monterey County, refer to Section 7, Dam and Levee Failure.
9.3.2 LANDSLIDES
Earthquakes can cause disastrous landslides. Landslides occur because of horizontal seismic inertia forces induced in the slopes by the ground shaking. The most common earthquakeinduced landslides include shallow, disrupted landslides such as rock falls, rockslides, and soil slides. Debris flows are created when surface soil on steep slopes becomes totally saturated with water. Once the soil liquefies, it loses the ability to hold together and can flow downhill at extremely high speeds, taking vegetation and/or structures with it. Slide risks increase after an earthquake during a wet winter.
For more information on landslide risk in Monterey County, refer to Section 15, Slope Failure.
9.3.3 TSUNAMIS
Depending on the location, earthquakes can trigger tsunamis. Tsunamis significantly damage many locations beyond what the earthquake struck; however, coastal communities near the earthquake epicenter that are also vulnerable to tsunamis could experience devastating impacts. As an Oceanic Plate is subducted beneath a Continental Plate, it sometimes brings down the lip of the Continental Plate with it. Eventually, too much stress is put on the lip, and it snaps back, sending shockwaves through the earth’s crust, causing a tremor under the sea, known as an Undersea Earthquake. Factors that affect tsunami generation from an earthquake event include magnitude (generally, a 7.5 magnitude and above), depth of event (a shallow marine event that displaces seafloor), and type of earthquake (thrust as opposed to strike-slip).
For more information on tsunami risk in Monterey County, refer to Section 16, Tsunami.
9.4 RISK ASSESSMENT
9.4.1 POPULATION
According to the FEMA National Risk Index, 415,057 people, or the entire population is exposed to earthquake risk. Whether directly impacted or indirectly impact, the entire population will Packet Page 348
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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.
As seen in Table 9-6, close to 200,000 people, almost half of the population of Monterey County, live in areas with high or moderate liquefaction susceptibility.
Table 9-6: Population Exposed to Areas Susceptible to Liquefaction Table 9-6
Population Exposed to Areas Susceptible to Liquefaction in Monterey County Supervisorial District High Moderate
District 1 23,680 3,256
District 2 45,825 9,223
District 3 14,729 24,549
District 4 7,622 19,936
District 5 35,764 14,625
Total 127,620 71,589
Residents in high-risk areas are more vulnerable to the impact of earthquakes. The degree of vulnerability is dependent on many factors, including the age and construction type of the structures people live in, the soil their homes are constructed on, and their proximity to the fault location, etc.
Two groups are particularly vulnerable to earthquake hazards: the population below the poverty level and those with access and functional needs. Those below the poverty level may lack the financial resources to improve their homes to prevent or mitigate earthquake damage.
Economically disadvantaged residents are also less likely to have insurance to compensate for losses in earthquakes. Those with access and functional needs are vulnerable because they are more likely to need special medical attention, which may not be available due to isolation caused by earthquakes. Some residents may also have more difficulty leaving their homes during earthquake events and could be stranded in dangerous situations.
9.4.2 PROPERTY
All structures in the County are susceptible to earthquake impacts to varying degrees. The most common type of damage from ground shaking is structural damage to buildings, which can range from cosmetic stucco cracks to total collapse. The overall level of structural damage from a nearby large earthquake would likely be moderate to heavy, depending on the characteristics of the earthquake, the type of ground, and the condition of the building. Besides damage to buildings, strong ground shaking can cause severe damage by falling objects such as bookcases or water heaters, or broken water or gas pipes. Fire and explosions resulting from ruptured gas pipes are also major hazards associated with strong ground shaking.
According to Monterey County Assessor records, there are 128,966 residential and nonresidential buildings in the County, with a total value of $73,489,253,104. Since all structures in Packet Page 349
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the County are susceptible to earthquake impacts to varying degrees, this represents the property exposure to seismic events.
Assessor’s data value total includes land value. Since following an earthquake, the land is likely to still have value even if the structure is destroyed, the exposed value is likely an overestimate.
Therefore, FEMA data was also included in this analysis in addition to the Assessor’s data.
According to the FEMA National Risk Index, in Monterey County, $41,169,506,000 in total building value is exposed to earthquake risk.
A large amount of property in the County is also exposed to liquefaction risk., As seen in Table 9-7, close to 20,000 residential properties, about $12 billion in property value is in areas with high or moderate liquefaction susceptibility. As seen in Table 9-8, close to 22,000 nonresidential properties, about $11 billion in property value is in areas with high or moderate liquefaction susceptibility.
Table 9-7: Residential Property Exposed to Areas Susceptible to Liquefaction Table 9-7
Residential Property Exposed to Areas Susceptible to Liquefaction in Monterey County Supervisorial
District
High Moderate
# Value # Value
District 1 673 $372,310,680 253 $133,011,281
District 2 3,547 $1,591,632,718 472 $282,454,095
District 3 1,838 $621,850,036 3,287 $948,153,442
District 4 837 $398,868,120 4,514 $1,933,056,731
District 5 3,729 $3,772,532,646 2,268 $1,882,248,356
Total 10,624 $6,757,194,200 10,794 $5,178,923,905
Table 9-8: Non-Residential Property Exposed to Areas Susceptible to Liquefaction Table 9-8
Non-Residential Property Exposed to Areas Susceptible to Liquefaction in Monterey County Supervisorial
District
High Moderate
# Value # Value
District 1 1,270 $827,677,352 922 $421,513,584
District 2 4,000 $1,109,321,385 1,638 $397,837,469
District 3 3,041 $1,851,569,790 3,273 $2,914,179,282
District 4 745 $744,052,338 2,608 $1,124,210,594
District 5 3,013 $1,754,854,558 1,147 $539,666,562
Total 12,069 $6,287,475,423 9,588 $5,397,407,491
Poorly constructed buildings and manufactured housing units are more vulnerable to structural failure during an earthquake, as well as secondary hazards such as utility disruption and urban conflagration. Older buildings are also more vulnerable to structural failure, as they may have been built before building and seismic code requirements that directly affect the structural integrity of development.
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Of particular concern in Monterey County is unreinforced masonry buildings, which are constructed from materials such as adobe, brick, hollow clay tiles, or other masonry materials and do not contain an internal reinforcing structure, such as rebar in concrete or steel bracing for brick. Unreinforced masonry poses a significant danger during an earthquake because the mortar holding masonry together is typically not strong enough to withstand significant earthquakes. The brittle composition of these buildings can break apart and fall away or buckle, potentially causing a complete collapse of the building.
9.4.3 CRI TICAL FACILITIES AND INFRASTRUCTURE
All critical facilities in the County are exposed to the earthquake hazard. Earthquakes pose numerous risks to critical facilities and infrastructure. Hazardous materials releases can occur during an earthquake from fixed facilities or transportation-related incidents. 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. Depending on the year of build and construction of each facility containing hazardous materials, the earthquake-initiated hazardous material release potential will vary.
Hazardous materials contained within masonry or concrete structures built before certain benchmark years may be particularly vulnerable.
Transportation corridors can be disrupted during an earthquake, leading to the release of materials to the surrounding environment. Linear utilities and transportation routes are vulnerable to rupture and damage during and after a significant earthquake event. The cascading impact of a single failure can have affects across multiple systems and utility sectors.
Degrading infrastructure systems and future large earthquakes with epicenters near critical regional infrastructure could result in system outages that last weeks for the most reliable systems, and multiple months for others.
Telecommunication systems can be affected by system failure, overloads, loss of electrical power and possible failure of some alternate power systems. Immediately following an event, numerous failures will occur, compounded by system use overload.
Large ground motions resulting from liquefaction, especially lateral spreading, can cause damage to buried pipelines. Most pipe breaks during the Loma Prieta earthquake were in areas with significant liquefiable soil. Broken pipelines represent a serious public safety issue as demonstrated by burning natural gas lines in the 1994 Northridge earthquake and broken water mains in San Francisco in the 1906 earthquake.
Critical facilities exposed to liquefaction risk are summarized in Table 9-9.
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Table 9-9: Critical Infrastructure in High Liquefaction Susceptibility Areas Table 9-9
Critical Infrastructure in High Liquefaction Susceptibility Areas in Monterey County Critical Infrastructure Type High Liquefaction Susceptibility Facilities
Emergency Response 5
Fire Station 7
Police Station 0
Medical Facilities 14
Military Facility 1
Large Public Facilities 0
Educational Facilities 17
Power Plant 1
Water & Wastewater Facilities 87
Stormwater Facilities 7
Government Facilities 53
Communication Facilities 175
Rain Gauges 17
Lighthouses 1
Dams 1
Hazardous Materials
Active or Idle Oil Well 250
Landfill 0
Underground Tank 39
Cal ARP Facility 11
Transportation
Airport 4
Bridge 111
Harbor 1
Highway/Freeway (Miles) 100
Driveway (Miles) 2
Major Road (Miles) 443
Local (Miles) 899
Railroad (Miles) 29
9.4.4 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 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. Streams fed by groundwater wells can dry up because of changes in underlying geology.
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9.4.5 ECONOMIC IMPACT
A large earthquake could have a massive economic impact on Monterey County. The number of economic damages will likely vary greatly due to a variety of factors including magnitude and location of the epicenter. Other than direct economic losses due to an earthquake, indirect economic consequences can occur due to business interruption and loss of functions of utilities.
9.5 FUTURE TRENDS IN DEVELOPMENT
Land use in the County will be directed by general plans adopted under California’s General Planning Law. The safety elements of the general plans establish standards and plans for the protection of the community from hazards. The information in this plan provides a tool to ensure that there is no increase in exposure in areas of high seismic risk. The geologic hazard portions of the County are heavily regulated under California’s General Planning Law.
Development in the County is also be regulated through building standards and performance measures so that the degree of risk will be reduced. The International Building Code establishes provisions to address seismic risk.
9.6 ISSUES
Important issues associated with earthquakes in Monterey County include the following:
• Unreinforced masonry buildings and building stock built prior to 1975, when seismic provisions became uniformly applied through building code applications, are a major concern in the event of a large earthquake.
• An earthquake could trigger other natural hazard events such as dam failures and landslides, which could severely impact the County.
• A worst-case scenario would be the occurrence of a large seismic event during a flood or high-water event. Levee failures could happen at multiple locations, increasing the impacts of the individual events.
• Citizens would be expected to be self-sufficient up to 3 days after a major earthquake without government response agencies, utilities, private-sector services, and infrastructure components.
• After a major seismic event, Monterey County is likely to experience disruptions in the flow of goods and services resulting from the destruction of major transportation infrastructure across the broader region.
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10. FLOODING
10.1 OVERVIEW
Flooding is the accumulation of water where usually none occurs or the overflow of excess water from a stream, river, lake, reservoir, or coastal body of water onto adjacent floodplains.
Floodplains are lowlands adjacent to water bodies that are subject to recurring floods. Floods are natural events that are considered hazards only when people and property are affected.
Nationwide, floods result in more deaths than any other natural hazard. Physical damage associated with floods includes the following:
• Inundation of structures, causing water damage to structural elements and contents. • Erosion or scouring of stream banks, roadway embankments, foundations, footings for bridge piers, and other features.
• Impact damage to structures, roads, bridges, culverts, and other features from highvelocity flow and from debris carried by floodwaters. Debris may also accumulate on bridge piers and in culverts, increasing loads on these features or causing overtopping. • Destruction of crops, erosion of soil, and deposition of debris and sediment on croplands.
• Release of sewage and hazardous or toxic materials as wastewater treatment plants are inundated, storage tanks are damaged, and pipelines are severed.
10.1.1 FLOODPLAINS
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, Packet Page 355
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as when a river is confined in a canyon. 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.
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.
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. Human activities can interface effectively with a floodplain as long as steps are taken to mitigate the activities’ adverse impacts on floodplain functions.
10.1.2 NATIONAL FLOOD INSURANCE PROGRAM
The NFIP makes federally backed flood insurance available to homeowners, renters, and business owners in participating communities. FEMA has prepared a detailed Flood Insurance Study for Monterey County and all incorporated areas, which was last revised in June of 2017. 34 The study presents water surface elevations for floods of various magnitudes, including the 1% annual chance flood (100-year flood) and the 0.2% annual chance flood (500-year flood).
Base flood elevations and the boundaries of the 100- and 500-year floodplains are shown on Flood Insurance Rate Maps (FIRMs), which are the principal tool for identifying the extent and location of the flood hazard. 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.
34 Federal Emergency Management Agency, Flood Insurance Study, Monterey County Packet Page 356
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• New floodplain development must exercise a reasonable and prudent effort to reduce its adverse impacts on threatened salmonid species.
As listed in Table 10-1, Monterey County and all incorporated cities participate in the NFIP.
Table 10-1: NFIP Coverage
Table 10-1
NFIP Coverage
Jurisdiction Community
Number
Policies
in Force Total Coverage Total Written Premium + Federal Policy Fee Carmel-By-The-Sea 060196 29 $9,940,000 $13,888
Del Rey Oaks 060197 19 $6,577,500 $50,436
Gonzales 060198 14 $5,474,500 $18,502
Greenfield 060446 3 $1,050,000 $1,260
King City 060199 17 $4,318,600 $28,721
Marina 060727 45 $13,664,400 $61,833
Monterey 060200 58 $19,847,400 $49,129
Monterey County 060195 1,277 $362,723,300 $1,732,791
Pacific Grove 060201 35 $11,144,000 $14,846
Salinas 060202 317 $95,459,500 $320,007
Sand City 060435 3 $1,400,000 $3,109
Seaside 060203 10 $2,789,000 $3,748
Soledad 060204 1 $350,000 $467
FEMA Regulatory Flood Zones
FEMA defines flood hazard areas as areas expected 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 FIRMs, which provide the following information:
• Locations of specific properties in relation to Special Flood Hazard Area (SFHAs) • Base flood elevations (1% annual chance) at specific sites • Magnitudes of flood in specific areas
• Undeveloped coastal barriers where flood insurance is not available • Regulatory floodways and floodplain boundaries (1% and 0.2% annual chance floodplain boundaries)
Land area covered by floodwaters of the base flood is the SFHA on a FIRM—an area where NFIP floodplain management regulations must be enforced, and where mandatory purchase of flood insurance applies. This regulatory boundary is a convenient tool for assessing vulnerability and Packet Page 357
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risk in flood-prone communities because many communities have maps showing the extent of the base flood and likely depths that would occur.
The base flood elevation (the water elevation of a flood that has a 1% chance of occurring in any given year) is one of the most important factors in estimating potential damage from flooding. A structure within a 1% annual chance floodplain has a 26% chance of undergoing flood damage during the term of a 30-year mortgage. The 1% annual chance flood is used by the NFIP as the basis for insurance requirements nationwide. FIRMs also depict 0.2% annual chance flood designations (500-year events). FIRMs, and other flood hazard information can be used to identify the expected extent of flooding from a 1% and 0.2% annual chance event. FIRM maps depict flood zones, defined in Table 10-2.
Table 10-2: FEMA Flood Zones
Table 10-2
FEMA Flood Zones
Flood Zone Definition
Special Flood Hazard Areas (SFHA) Subject to Inundation by 100-Year Flood Zone A No base flood elevations determined
Zone AE Base flood elevations determined
Zone AH Flood depths of 1-3 feet (usually areas of ponding); base flood elevations determined
Zone AO
Flood depths of 1-3 feet (usually sheet flow on sloping terrain); average depths determined; for areas of alluvial fan flooding, velocities also determined
Zone AR
SFHA formerly protected from the 1% annual chance flood by a flood control system that was subsequently decertified; zone AR indicates that the former flood control system is being restored to provide protection from the 1% annual chance or greater flood
Zone A99
Area to be protected from 1% annual chance flood by a federal flood protection system under construction; no base flood elevations determined
Zone VE
Area where waves and fast-moving water can cause extensive damage during the base flood event. Wave heights are larger than 3 feet. A detailed study has been done and BFEs have been calculated.
Other Flood Areas
Zone X (shaded)
Areas of 0.2% annual chance flood (i.e., 500-year flood); areas of 1% annual chance flood with average depths of less than 1 foot or with drainage areas less than 1 square mile; and areas protected by levees from 1% annual chance flood
Other Areas
Zone X (unshaded) Areas determined to be outside the 0.2% annual chance floodplain Zone D Areas in which flood hazards are undetermined, but possible Packet Page 358
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Community Rating System (CRS)
The Community Rating System (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 that meet the three goals of the CRS: 1) reduce flood losses, 2) facilitate accurate insurance rating, and 3) promote awareness of flood insurance.
Flood insurance premium rates in Community Rating System communities are discounted in increments of 5%. A Class 10 community is not participating in the CRS and receives no discount. A Class 9 community receives a 5% discount for all policies in its Special Flood Hazard Areas, a Class 8 community receives a 10% discount, all the way to a Class 1 community, which receives a 45% premium discount. The CRS classes for local communities are based on 18 creditable activities related to public information, mapping and regulations, flood damage reduction, and flood preparedness. As noted in Table 10-3, Monterey County and the City of Salinas are currently participating in the CRS program.
Table 10-3: Community Ratings System (CRS) Participation Table 10-3
Community Ratings System (CRS) Participation
Community
Name
CRS Entry
Date
Current
Effective Date
Current
Class
Discount for
SFHA
Discount for
Non- SFHA
Monterey County 10/1/1991 10/1/2020 5 25% 10%
Salinas 10/1/1991 10/1/2013 7 15% 5%
10.1.3 TYPES OF FLOODING
In Monterey County four types of flooding occur: riverine flooding, coastal flooding, flash flooding, and stormwater runoff flooding.
Coastal Flooding
Coastal or 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 near bay waters.
Coastal flooding in Monterey County is generally associated with Pacific Ocean storms in the months of November through February. Coastal flooding in conjunction with high tides and strong winds is a significant hazard.
Riverine Flooding
Riverine flooding is overbank flooding of rivers and streams. 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 Packet Page 359
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major rivers. Riverine floodplains range from narrow, confined channels in the steep valleys of mountainous and hilly regions to wide, flat areas in plains and coastal regions. The amount of water in the floodplain is a function of the size and topography of the contributing watershed, the regional and local climate, and land use characteristics. Flooding in steep, mountainous areas is usually confined, strikes with less warning time, and has a short duration. Larger rivers typically have longer, more predictable flooding sequences and broad floodplains.
Flash Flooding
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 floodwaters.
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.
Localized Stormwater Flooding
Urban storm drainpipes and pump stations have a finite capacity, and prolonged heavy rainfall contributes to a large volume of runoff resulting in high peak flows of moderate duration.
When rainfall exceeds this capacity, or the system is clogged, water accumulates in the street until it reaches a level of overland release.
Urban drainage systems can play a role in flooding in two ways:
• 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 in the area
• If stormwater runoff exceeds the capacity of the drainage system, then stormwater runoff flooding can result throughout the system’s service area. This is especially likely when groundwater levels are high and during high tides.
Stormwater flooding may occur outside of recognized drainage channels or delineated floodplains due to a combination of locally heavy precipitation, increased surface runoff, and inadequate facilities for drainage and stormwater conveyance. Such events frequently occur in flat areas and in urbanized areas with large impermeable surfaces. Local drainage may result in “nuisance flooding,” in which streets or parking lots are temporarily closed, and minor property damage occurs.
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10.1.4 WATERSHEDS IN MONTEREY COUNTY
Monterey County consists of four predominant watersheds draining to the Salinas River, the Pajaro River, the Carmel River, and the Big Sur River. These watersheds vary in patterns of land use from rural open space and permanent grazing to farmland and agricultural industrial, to low, medium, and high-density residential use. Increased development over the past 100 years has resulted in increased runoff that poses a flood threat. To accommodate the increasing runoff, many cities and communities in these watersheds have developed an extensive system of channels and storm drain facilities. The overall drainage pattern in the county is from south to north; this is the direction of flow for the Salinas River which is the largest river on the central coast of California. Watersheds in Monterey County are mapped in Figure 10-1.
Figure 10-1
Watersheds in Monterey County
Figure 10-1: Watersheds in Monterey County
Source: Monterey County Water Resources Agency (MCWRA)
The four predominant watersheds are described and listed in order of magnitude, from largest to smallest.
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Salinas River Watershed
The Salinas River Watershed originates 4,000 feet above sea level in the La Panza Range near Santa Margarita in San Luis Obispo County and drains a 4,200 square mile area. The Gabilan and Santa Lucia Ranges are the sources of the principal watercourses in the area. The Salinas River has three main tributaries, namely, the Nacimiento, San Antonio, and Arroyo Seco Rivers. It flows for over 110 miles within Monterey County and empties into the Monterey Bay.
Pajaro River Watershed
The Pajaro River Watershed originates from 4,700 feet above sea level in the Diablo and Gabilan Ranges in San Benito County and drains a 1,300 square mile area. The watershed is bound by the Santa Cruz Mountains in the north, and the Gabilan Range in the south. The watershed area spans four counties, namely, Santa Cruz, Santa Clara, San Benito, and Monterey. The Pajaro River has numerous tributaries, which include Corralitos, Uvas, Llagas, San Benito, Pacheco, and Santa Ana Creeks, and flows for approximately 30 miles where it empties into Monterey Bay.
Carmel River Watershed
The Carmel River Watershed originates 4,000 feet above sea level in the Santa Lucia Range and drains a 256 square mile area. The Carmel River has two main tributaries, Cachagua and Tularcitos Creeks, and flows for approximately 26 miles where it empties into the Pacific Ocean.
Big Sur River Watershed
The Big Sur River Watershed originates from 3,000 feet above sea level along Pine Ridge in the Santa Lucia Mountains and drains a 60 square mile area. The Big Sur River has numerous tributaries which include Redwood Creek, Ventana Creek, Post Creek, and Pfeiffer-Redwood Creek, and flows for approximately 15 miles where it empties into the Pacific Ocean.
10.2 HAZARD PROFILE
10.2.1 HISTORY
Historic records show flooding and flood damage have occurred on a fairly regular basis (every few years) within Monterey County. The County experienced severe damages in:
January 1966: Flood conditions along the length of the Salinas River caused extensive damage during the storm of January 1966. Most of this damage was to agricultural crops; over 32,000 acres were inundated, at an estimated loss of $6,572,000. The cities in the county experienced some flooding and damage, although the rural areas and agricultural production were the most affected, with Salinas Valley agriculture sustaining a $3,755,000 loss. 1969: There were two distinct floods in 1969, one at the end of January and one at the end of February. In each flood, both the Salinas and Carmel Rivers flooded. Damage from the storms was extremely costly, causing an estimated $16 million in damages.
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1978: A series of storms emanating from a southerly direction, caused extensive beachfront and coastal damage. Persistent rains in the Salinas Valley, caused an estimated $20,000,000 in flood damages, flooding more than 20,000 acres of irrigated farmland, with as much as 1,000 acres of the prime farmlands flooded beyond agricultural use for the year.
March 1983: “El Niño” storms brought an extremely unusual series of high tides, storm surges, and storm waves along the coast, and heavy rains causing extensive flooding and erosion in the Salinas Valley. Farmland and roadways were damaged, and Monterey County was declared a disaster area.
January 1995: In January 1995, a 10- to 20-year event caused prolonged and sustained precipitation resulting in extensive flooding throughout the region. Most river valleys were affected, with major damage experienced in the Pajaro Valley and Carmel Valley. Five localized areas within the Carmel Valley area were significantly affected by downstream flooding of the Carmel River. The January 1995 flood damaged 125 residences resulting in an estimated damage cost of approximately $2.5 million. In addition, an estimated $927,000 in damage to public facilities and utilities occurred.
March 1995: From March 10-13, 1995, Monterey County experienced a second significant winter storm which resulted in sustained precipitation falling on already-saturated watersheds.
Devastating flooding occurred throughout the County, particularly along the Carmel, Arroyo Seco, Salinas, and Pajaro Rivers. Damage was extensive throughout the County with virtually every community affected. Pajaro, Castroville, Mission Fields, Carmel Valley, Cachagua, Carmel Highlands, Spreckels, and Big Sur sustained devastating damage. Over 1,500 residences were damaged, including 60 homes which were declared uninhabitable. In addition, an estimated 100 businesses were affected, and the tourism industry sustained substantial losses for a period of several months.
In all, over 11,000 people were directly affected, and major portions of the County's agricultural lands subjected to widespread destruction. At the height of the flood, 63 roads and 15 bridges were closed, including the Highway 1 bridge over the Carmel River. The closure of the Highway 1 bridge over the Carmel River resulted in the complete elimination of access to portions of Carmel Valley, Carmel Highlands, and Big Sur for a period of several days, requiring evacuations to take place with helicopters.
62 roads and three bridges sustained damage. Public and private water systems were damaged, affecting approximately 3,500 homes and businesses. Eight large water systems and over fifty small systems were affected. Many residents were without domestic water service for extended periods. A number of areas were required to boil domestic water prior to use.
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Sewage treatment facilities and private septic systems along all three major rivers (Carmel, Salinas, and Pajaro) were flooded and untreated sewage was released into the rivers. The amount of untreated sewage released could not be confirmed, but it may have been many thousands of gallons. Major treatment plants affected included Carmel Ranch, Watsonville, King City, Soledad, and Gonzales. Gas and electric service provided by Pacific Gas and Electric were affected by the storm, resulting in serious
disruptions in service to widespread areas.
Many public facilities and services were closed
or interrupted, including public schools in
affected communities. Zmudowski State
Beach was closed as a result of the discovery
of 27 barrels of potentially hazardous
materials on the beach.
February 1998: A series of "El Niño" winter
storms hit Monterey County and the close
timing of the rainfall events contributed to
intense flooding and saturated ground. An
estimated 50 roads and highways were closed
or restricted, in most cases due to washouts,
landslides, and mudslides. Several
communities were evacuated, including
Pajaro’s entire population of 3,500 people,
after the levee along the Pajaro River was
breached in several places.
Drinking water quality warnings remained in
effect for certain areas for some time
afterward. By the end of the first week of
February, at least 6,600 homes and businesses
had been without power for varying periods
of time. Countywide losses from that storm
were estimated at over $38 million, with
agriculture-related losses totaling over $7
million and involving approximately 29,000
damaged acres.
In the 1998 storm event, the Las Lomas area
experienced severe damage of eight
residential parcels. Monterey County acquired
the parcels through the Federal Hazard
Mitigation Success Story
Severe Repetitive Loss Property Elevation
In 2015, Monterey County completed the
elevation of a Severe Repetitive Loss (SRL)
structure located along the Carmel River.
Based on historical data and FEMA flood
mapping it can be assumed this structure
would have sustained damages during the
major flood events in 2017 and 2019.
In 2017 damages would have been minimal,
with estimated flooding at 1.5 feet above
the finished floor elevation. This would have
resulted in about $83,652 in damages with
no mitigation. With mitigation, it is
estimated that no damage would have
occurred, a savings of $83,652.
In 2019, significant flooding of up to 6 feet
above the finished floor elevation would
have resulted in approximately $255,718 in
damages with no mitigation. With mitigation
it is estimated that $88,946 in damages
would have resulted from flood depths of 6
feet, a savings of $166,772.
Taking in to account each event, this project
has a combined estimated savings of
$250,424 since its completion in 2015.
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Mitigation Grant Program and all structures were removed. Each parcel was subsequently rezoned to “open space” in perpetuity.
January 2008: A strong coastal storm in January 2008 brought flooding rains, high winds, record high surf, and coastal flooding to Monterey County and resulted in nearly $1 million in property damages. Approximately 30 homes in the Carmel Lagoon area were affected by some degree of flooding.
October 2010: In October 2010, a strong lowpressure system made its way through Central California and led to record breaking
heavy rains across the area, causing an
estimated $200,000 in damages. In Salinas,
the Pacific Coast Christian Academy and Little
Lamb Preschool were flooded after Little Bear
Creek breached its banks.
March 2011: A series of systems affected
Monterey County with heavy rain and strong
winds causing an estimated $1 million in
property damages. Nearly 1,300 acres of
crops or croplands were impacted by flooding
from the Salinas River and its tributaries
causing an estimated $1.5 million in losses.
December 2014: An atmospheric river
brought heavy rain, gusty winds, and a strong
winter storm that impacted the region for
several days in mid-December. The Moro Cojo
Slough backed up and flooded homes and
roadway along its banks. Sandbagging
operations were needed to protect the homes
from significant damage. The slough flap
gates were damaged and could not properly
drain the slough into Moss Landing Harbor.
The unincorporated community of Bolsa
Knolls along Santa Rita Creek was flooded
when a nearby levee broke open. Emergency
crews reported that homes on Paul Avenue
and Russell Road where evacuated and more
than 18 inches of water flooded homes in a
short amount of time. Fifteen homes were
Mitigation Success Story
Salinas River Stream Maintenance Program
Monterey County is subject to major flood
events along the Salinas River. In 2016,
programmatic permits were approved for the
Salinas River Stream Maintenance Program
(SMP). The Salinas River SMP was developed
as a collaboration between the Monterey
County Water Resources Agency, the
Resource Conservation District of Monterey
County (RCDMC), the Salinas River Channel
Coalition, the Grower Shipper Association of
Central California, The Nature Conservancy,
and the Conservation Collaborative.
The SMP employs a multi-benefit approach
for stream maintenance that enhances
conveyance capacity of the river corridor by
mimicking the sandy-bottomed river’s
natural, braided form in a manner that
protects habitat, while reducing flood risk.
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flooded and damaged due to flooding along Santa Rita Creek. The heavy rain also overwhelmed the sewage plant in Castroville resulting in a sewage spill. 2016: Monterey County was hit with several significant storm events during the 2016 El Niño winter. The first one took place on January 19, 2016, the second from March 5 and 6, 2016, and the third on March 11, 2016. These storms caused severe roadway damage totaling $7,318,000 in repair costs.
2017: A series of atmospheric river events in January and February of 2017 caused widespread roadway flooding and damage in Monterey County. Combined, the January and February storms caused an estimated $52 million to County roads. 2019: An atmospheric river caused widespread heavy rainfall, roadway flooding, and strong winds. This caused flash flooding in Chualar where homes were flooded, and cars were stranded on a flooded highway. This event caused an estimated $2 million in damages.
10.2.2 LOCATION
Principal Flooding Sources
FEMA’s Flood Insurance Study for Monterey County assessed several creeks, channels, and water bodies, including the following flooding sources:
• Arroyo Seco • El Toro Creek • Salinas River
• Big Sur River • Elkhorn Slough • San Benancio Gulch
• Bixby Creek • Gabilan Creek • San Jose Creek
• Calera Creek • Gonzales Slough • San Lorenzo Creek
• Canyon Del Rey • Harper Creek • San Miguel Canyon Creek • Carmel River • Josselyn Canyon Creek • Santa Rita Creek • Castroville Boulevard Wash • Little Sur River • Seal Rock Creek • Corncob Canyon Creek • Natividad Creek • Tembladero Slough • Del Monte Lake • Pajaro River • Tomasello Creek
• East Branch Gonzales Slough • Pine Canyon Creek • Watson Creek • El Estero Lake
Shallow (1- to 3-foot) and sheet flooding conditions generally occur in the Salinas, Carmel, Pajaro, and Big and Little Sur Valleys. In addition, flooding can occur along the beach, where it is not uncommon to see winter storms produce 15-foot breakers. Flooding in these areas generally occurs during the rainy season, from October to April.
Figure 10-2 shows the extent of the 100-year and 500-year floodplains, as well as the known localized flooding within the entire County according to current effective FIRMs (2017).
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Figure 10-2: FEMA Flood Zones
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Flood Awareness Zones
Flood Awareness Zones have been developed by California DWR to map areas of additional flood threat throughout the state. The intent of the Awareness Floodplain Mapping project is to identify all pertinent flood hazards for areas that are not mapped under the NFIP and to provide the community and residents an additional tool in understanding potential flood hazards currently not mapped as a regulated floodplain. The awareness maps identify the 100-YR flood hazard areas using approximate assessment procedures. These floodplains are shown simply as flood prone areas without specific depths and other flood hazard data.
Figure 10-3
DWR Flood Awareness Zones
Figure 10-3: DWR Flood Awareness Zones
Flood Insurance Claims
A repetitive loss (RL) area is an area where multiple properties in close proximity to each other have experienced repetitive losses from flooding. RL property is a FEMA designation, defined as an insured property that has made two or more claims of more than $1,000 in any rolling 10- year period. RL properties may be classified as a Severe Repetitive Loss (SRL) property under certain conditions. A SRL property has had four or more claims of at least $5,000, or at least two claims that cumulatively exceed the building’s value. A property that sustains repetitive flooding may or may not be on the County’s RL property list for a number of reasons:
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• Not everyone is required to carry flood insurance.
• Owners who have completed the terms of their mortgage or who purchased their property outright may choose not to carry flood insurance and instead bear the costs of recovery on their own.
• The owner of a flooded property that does carry flood insurance may choose not to file a claim. Even insured properties that are flooded regularly with filed claims may not meet the $1,000 minimum threshold to be recognized as an RL property. • The owner adopted mitigation measures that reduce the impact of flooding on the structure, removing it from the RL threat and the RL list.
Many jurisdictions are required to address only the properties on the RL list. These properties are representative of the community’s overall repetitive flooding problem, but do not include all damage. The Privacy Act of 1974 restricts the release of certain types of data to the public.
Flood insurance policy and claims data are included in the list of restricted information. FEMA can only release such data to state and local governments, and only if the data are used for floodplain management, mitigation, or research. Therefore, this plan does not identify RL properties or include claim data for any individual property. Flood insurance statistics on loss can still help identify locations vulnerable to flooding, therefore Table 10-4 summarizes loss statistics by jurisdiction.
Table 10-4: NFIP Loss Statistics for Monterey County
Table 10-4
NFIP Loss Statistics for Monterey County
Jurisdiction Community Number Total Losses Claims Total Net Dollars Paid Carmel-By-The-Sea 060196 3 $127,113
Del Rey Oaks 060197 1 $750
Gonzales 060198 10 $187,853
Greenfield 060446 1 $0
King City 060199 12 $715,518
Marina 060727 0 $0
Monterey 060200 37 $2,654,717
Monterey County 060195 1,163 $23,735,682
Pacific Grove 060201 1 $6,784
Salinas 060202 31 $160,884
Sand City 060435 0 $0
Seaside 060203 2 $125,032
Soledad 060204 0 $0
Total 1,261 $27,714,334
10.2.3 FREQUENCY
Monterey County has experienced 10 significant flood events since 1995. This indicates an approximate 38% chance of a significant and damaging flood event in any given year, with a recurrence interval of 2.6 years. Smaller floods may occur more frequently and are an annual Packet Page 369
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hazard. The FEMA National Risk Index calculates an annualized frequency value for riverine and coastal flood hazards in Monterey County. For flooding, annualized frequency was based on the number of distinct hazard events that have occurred. Flooding in Monterey County has an annualized frequency of 2.7 distinct coastal flood events per year and 0.95 distinct riverine flood events per year.
10.2.4 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. Shallow flooding with high velocities can cause as much damage as deep flooding with slow velocity. This is especially true when a channel migrates over a broad floodplain, redirecting high velocity flows and transporting debris and sediment. Although jurisdictions can implement mitigation and take preventative actions to significantly reduce the 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 prevent it). Threats associated with residual risk include failure of a reservoir, a dam, levee, or other infrastructure, or a severe flood event that exceeds flood design standards or drainage capacity.
Flood risk has increased with population and urbanization. Increased impervious surfaces and channelization of streams has resulted in increased runoff and intensified flood flows. Increased development in floodplains has put more property and lives at risk for flooding. The damages caused by flooding in the Salinas Valley today, even with the construction of major flood control infrastructure, are far more substantial than they were a century ago. Along the Big Sur coast, streams and rivers draining the steep coastal mountains are subject to short, intense floods, capable of producing significant damage to property. Wildfires also exacerbate flood risk in Big Sur, denuding areas of vegetation, which can lead to increased sheet flow and greater velocities during subsequent rainstorms and causing water quality problems in coastal waters. The impact and severity of coastal flooding is additionally affected by tides, storm surge (the rise in water from wind stress and low atmospheric pressure), waves, and peak still-water elevation.
10.2.5 WARNING TIME
Due to the sequential pattern of meteorological conditions needed to cause serious flooding, it is unusual for a flood to occur without warning. Warning times for floods can be between 24 and 48 hours. Flash flooding can be less predictable, but potential hazard areas can be warned in advanced of potential flash flooding danger. The Monterey County Water Resources Agency (MCWRA) provides flood warning services to Monterey County. MCWRA staff monitors county wide hydrologic conditions during every significant storm event. A real time flood warning system allows MCWRA staff to provide hydrologic data as well as expertise to emergency managers and local law enforcement any hour of the day or night as needed for the protection of life and property in Monterey County.
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10.3 SECONDARY HAZARDS
The most problematic secondary hazard for flooding is erosion, which in some cases can be more harmful than actual flooding. Flooding is also responsible for landslides when high flows over-saturate soils on steep slopes and cause them to fail. Hazardous materials spills are a secondary hazard of flooding if storage tanks rupture and spill into streams or storm sewers. It is also recognized that wildland fires within a watershed can exacerbate the flood hazard by virtue of increased rate and volume of runoff and attendant erosion and sediment discharge.
10.4 RISK ASSESSMENT
10.4.1 POPULATION
As seen in Figure 10-4, in Monterey County, 80,461 people are located in the 1% annual chance flood zone.
Figure 10-4
Population Exposed to Flood Risk
Figure 10-4:Population Exposed to Flood Risk
Floods can be extremely dangerous, and even six inches of moving water can knock over a person given a strong current. A car will float in less than two feet of moving water and can be swept downstream into deeper waters. This is one reason floods kill more people trapped in vehicles than anywhere else. During a flood, people can also suffer heart attacks or electrocution due to electrical equipment short outs.
Certain health hazards are also common to flood events. Standing water and wet materials in structures can become breeding grounds for microorganisms such as bacteria, mold, and viruses. This can cause disease, trigger allergic reactions, and damage materials long after the 10,103
26,848
13,259 12,532
17,719
73,833
43,213
23,274
47,109
14,568
0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
District 1 District 2 District 3 District 4 District 5
Monterey County Supervisorial District
1% Chance Annual 0.2% Chance Annual
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flood. When floodwaters contain sewage or decaying animal carcasses, infectious disease becomes a concern. Direct impacts, such as drowning, can be limited with adequate warning and public education about what to do during floods. Where flooding occurs in populated areas, warning and evacuation will be of critical importance to reduce life and safety impacts.
10.4.2 PROPERTY
As noted in Table 10-5, about 35,000 residential properties, almost $16 billion in property value, in Monterey County is in a mapped FEMA Flood Zone.
Table 10-5: Residential Property Exposed to Flood Risk by Flood Zone Table 10-5
Residential Property Exposed to Flood Hazard Risk by Flood Zone Supervisorial
District
1% Annual Chance 0.2% Annual Chance
# Value # Value
District 1 340 $215,814,543 9,716 $3,363,261,908
District 2 1,094 $496,002,748 7,941 $3,458,129,047
District 3 656 $183,474,624 3,550 $1,032,959,384
District 4 118 $67,526,512 10,974 $4,751,738,760
District 5 1,992 $2,729,269,901 1,298 $1,043,994,419
Total 4,200 $3,692,088,328 33,479 $13,650,083,518
As noted in Table 10-6, over 20,000 non-residential properties, about $10 billion in property value, in Monterey County is in a mapped FEMA Flood Zone.
Table 10-6: Non-Residential Property Exposed to Flood Risk by Flood Zone Table 10-6
Non-Residential Property Exposed to Flood Hazard Risk by Flood Zone Supervisorial
District
1% Annual Chance 0.2% Annual Chance
# Value # Value
District 1 423 $218,575,592 4,405 $1,607,035,317
District 2 2,697 $854,792,968 3,207 $739,146,623
District 3 2,133 $2,351,465,862 2,193 $724,778,875
District 4 388 $570,972,637 4,513 $1,479,403,355
District 5 1,734 $1,173,086,410 1,022 $508,954,540
Total 7,375 $5,168,893,469 15,340 $5,059,318,710
10.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
Flood events can significantly impact road bridges. These are important because often they provide the only ingress and egress to some neighborhoods. Roads or railroads that are blocked or damaged can isolate residents and can prevent access throughout the County, including for emergency service providers needing to get to vulnerable populations or to make repairs.
Additionally, underground utilities can be damaged. 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 Packet Page 372
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get into drinking water supplies, causing contamination. Sewer systems can be backed up or overwhelmed by inflow and infiltration, causing sanitary sewer overflows.
Facilities that are known to manufacture, process, store, or otherwise use hazardous materials could be damaged in a flood. If damaged by a flood, these facilities could release chemicals that cause cancer or other significant adverse acute human health effects, or significant adverse environmental effects. During a flood, containers holding these materials can rupture and leak into the surrounding area, disastrously affecting the environment and residents. Table 10-7 summaries critical infrastructure in the 100-year floodplain in Monterey County. Table 10-7: Critical Infrastructure in the 100-Year Floodplain Table 10-7
Critical Infrastructure in the 100-Year Floodplain in Monterey County Critical Infrastructure Type 1% Annual Chance
Facilities
Emergency Response 0
Fire Station 2
Police Station 0
Medical Facilities 3
Military Facility 0
Large Public Facilities 0
Educational Facilities 6
Power Plant 0
Water & Wastewater Facilities 61
Stormwater Facilities 8
Government Facilities 20
Communication Facilities 78
Rain Gauges 19
Lighthouses 0
Dams 0
Hazardous Materials
Active or Idle Oil Well 853
Landfill 0
Underground Tank 15
Cal ARP Facility 9
Transportation
Airport 1
Bridge 93
Harbor 3
Highway/Freeway (Miles) 89
Driveway (Miles) 1
Major Road (Miles) 310
Local (Miles) 527
Railroad (Miles) 23
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10.4.4 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.
While the vulnerability assessment focuses on human vulnerability to flood events, the impact of human activities on flooding is also worth noting. Due to negative impacts of floods, many structural and other measures have been devised to limit how far a floodplain can extend.
However, floodplains have many natural and beneficial functions, and disruption of natural systems can have long-term consequences for entire regions.
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 conveyance • Process organic wastes • Reduce flood velocities • Moderate temperatures of water • Reduce flood peaks • Surface water quality maintenance • Reduce sedimentation • Promote infiltration and aquifer recharge Areas in the floodplain that typically provide these natural functions are wetlands, riparian areas, sensitive areas, and habitats for rare and endangered species.
10.4.5 ECONOMIC IMPACT
Flooding can result in economic losses through closure of businesses and government facilities, disrupt communications, disrupt the provision of utilities such as water and sewer service, result in excessive expenditures for emergency response, and generally disrupt the normal function of a community.
Locations that are directly flooded experience the greatest economic impact. In these areas, renovations of commercial buildings may be necessary, disrupting associated services.
Significant damage may occur in agricultural areas, with destruction of crops and agricultural products. The tourism industry may 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 or running on backup generator power.
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10.5 FUTURE TRENDS IN DEVELOPMENT
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 the safety elements of their General Plans. Additionally, all municipal planning partners are participants in the NFIP and have adopted flood damage prevention ordinances in response to its requirements. All municipal planning partners have committed to maintaining their good standing under the NFIP through actions identified in this plan.
10.6 ISSUES
Important issues associated with flooding in Monterey County include the following:
• The accuracy of the existing flood hazard mapping produced by FEMA in reflecting the true flood risk within the County is questionable.
• The effect of climate change on flood risk is uncertain. • More information is needed on flood risk to support the concept of risk-based analysis of capital projects.
• Ongoing flood hazard mitigation will require funding from multiple sources. • 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. • The economy affects a jurisdiction’s ability to manage its floodplains. Budget cuts and personnel losses can strain resources needed to support floodplain management.
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11. HAZARDOUS MATERIALS
INCIDENT
11.1 OVERVIEW
According to the Environmental Protection Agency (EPA), a hazardous material is any item or agent (biological, chemical, physical) which has the potential to cause harm to humans, animals, or the environment, either by itself or through interaction with other factors. These substances may be highly toxic, reactive, corrosive, flammable, radioactive, or infectious.
Hazardous materials can be present in any form, gas, solid, or liquid. Environmental or atmospheric conditions can influence hazardous materials if they are uncontained. Hazardous materials include hundreds of substances that pose a significant risk to humans.
Title 49 of the Code of Federal Regulations (CFR) lists thousands of hazardous materials, including gasoline, insecticides, household cleaning products, and radioactive materials. Stateregulated substances that have the greatest probability of adversely impacting the community are listed in the CCR, Title 19. Numerous federal, state, and local agencies, including the US Environmental Protection Agency (EPA), US Department of Transportation (DOT), National Fire Protection Association, FEMA, the US Army, and the International Maritime Organization regulate hazardous materials.
Hazardous material releases can pose a risk to life, public health, air quality, water quality and the environment. A release or spill of bulk hazardous materials could result in fire, explosion, toxic cloud or direct contamination of water, people, and property. The effects may involve a Packet Page 377
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local area or many square miles. They may result in the evacuation of a facility or an entire neighborhood. In addition to the immediate risk, long-term public health and environmental impacts may result from sustained exposure to certain substances. Damage to property could range from immediate destruction by explosion to permanent contamination by a persistent hazardous material.
Natural hazards may cause the release of hazardous materials and complicate response activities. The impact of earthquakes on fixed facilities may be particularly serious due to the impairment or failure of the physical integrity of containment facilities. The threat of any hazardous material event may be magnified due to restricted access, reduced fire suppression and spill containment, and even complete cut-off of response personnel and equipment.
11.1.1 TYPES OF HAZARDOUS MATERIALS INCIDENTS
The following are the most common types of hazardous material incidents:
• Fixed Facility Hazardous Materials Incident: This is the uncontrolled release from a fixed site of materials that pose a risk to health, safety, and property. Fixed site facilities include refineries, chemical plants, storage facilities, manufacturing facilities, warehouses, wastewater treatment plants, swimming pools, dry cleaners, automotive sales/repair, and gas stations. It is possible to identify and prepare for fixed-site incidents because federal and state laws require those facilities to notify state and local authorities about materials being used or produced at the site. • Hazardous Materials Transportation Incident: A hazardous materials transportation incident is any event during transport resulting in uncontrolled release 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. Transported hazardous wastes include thousands of shipments of radiological materials moved across the United States by ground transportation, mostly medical materials, and low-level radioactive waste. Hazardous materials transportation incidents can occur on any transportation corridor, although most occur on interstate highways, other major federal or state highways, or major rail lines. Accidents may involve bulk petroleum products, reactive materials, chemical wastes, explosives, and other toxic substances that are being transported or temporarily stored while in transit.
• Interstate Pipeline Hazardous Materials Incident: There are a significant number of interstate natural gas, heating oil, and petroleum pipelines running through the State of California. These are used to provide natural gas to utilities and to transport these materials from production facilities to end-users.
Hazard Materials Classifications
The US Department of Transportation (USDOT) divides hazardous materials into nine major hazard classes. A hazard class is a group of materials that share a common major hazardous property, i.e., radioactivity, flammability, etc. These hazard classes include:
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• Class 1: Explosives
• Class 2: Compressed Gases
• Class 3: Flammable Liquids
• Class 4: Flammable Solids; Spontaneously Combustible Materials; Dangers When Wet Materials/Water-Reactive Substances
• Class 5: Oxidizing Substances and Organic Peroxides
• Class 6: Toxic Substances and Infectious Substances
• Class 7: Radioactive Materials
• Class 8: Corrosives
• Class 9: Miscellaneous Hazardous Materials/Products, Substances, or Organisms
11.1.2 OVERSIGHT
Hazardous materials management is regulated by federal and state codes. The state fire marshal and the Pipeline and Hazardous Materials Safety Administration enforce oil and gas pipeline safety regulations. The federal government enforces hazardous material transport pursuant to its interstate commerce regulation authority. The Department of Toxic Substances Control (DTSC), a Division of the California Environmental Protection Agency, acts to protect California from exposure to hazardous waste by cleaning up existing contamination and looking for ways to reduce the amount of hazardous waste produced. DTSC regulates hazardous waste primarily under the authority of the Federal Resource Conservation and Recovery Act and the California Health and Safety Code. Other laws that affect hazardous waste are specific to handling, storage, transportation, disposal, treatment, cleanup, and emergency planning. DTSC has the authority to implement permitting, inspection, compliance, and corrective action programs to ensure that people who manage hazardous waste follow requirements.
Businesses are required to disclose all hazardous materials and waste above certain designated quantities that they use, store, or handle at their facility. They must prepare chemical inventory and business emergency plans, review the plans regularly, and conduct training. Any release or possible release of hazardous materials must be reported to the Cal OES Warning Center.
Businesses using certain regulated substances (about 260 specific flammable or toxic chemicals) must develop a risk management plan. The plan must include an analysis of operations on-site, and projection of off-site consequences with accompanying mitigation plans.
11.2 HAZARD PROFILE
11.2.1 HISTORY
According to data from Cal OES Warning Center from 2016 through June 2, 2021. The records show 667 hazardous materials spills in Monterey County over the 5-year timeframe. Table 11-1 lists the number of hazardous material incidents by spill site and type of substance spilled in Monterey County reported to the Cal OES Warning Center.
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Table 11-1: Hazardous Materials Spills by Spill Site and Substance Spilled (2016-2021) Table 11-1
Hazardous Materials Spills in Monterey County by Spill Site and Substance Spilled (2016-2021) Spill Site
Type of Substance Spilled
Chemical Petroleum Radiological Sewage Vapor Unnamed
/ Other
Railroad
Derailment Total
Airport 1 1 2
Industrial 2 4 5 2 13
Business 10 21 29 15 14 89
Military Base 6 3 1 10
Oil Field 17 1 18
Other 7 24 29 7 10 77
Pipeline 1 1
Railroad 1 2 1 1 44 49
Residence 3 8 83 4 3 101
Road 4 51 2 53 2 2 114
School 1 5 1 7
Gas Station 13 1 14
Ship/ Harbor 1 18 1 2 22
Sewage
Facility 1 1 8 2 12
Utilities/
Substation 3 1 4
Waterways 2 106 13 13 134
Total 31 277 2 228 34 51 44 667
Source: Cal OES Spill Release Reporting Data (2016 through June 2, 2021) As seen in Table 11-2, the most common causes of hazardous materials incidents were unknown (26%), followed by blockages (18%) and mechanical (18%).
Table 11-2: Hazardous Materials Spills by Cause of Spill (2016-2021) Table 11-2
Hazardous Materials Spills in Monterey County by Cause of Spill (2016-2021) Cause Number
Blockage 121
Broken Pipe 20
Collision 57
Human Error 96
Mechanical 117
Other 67
Overflow 15
Rail 1
Unknown 173
Total 667
Source: Cal OES Spill Release Reporting Data (2016 through June 2, 2021) Packet Page 380
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Of the 667 reported incidents, 175 (26%) occurred in unincorporated Monterey County, including 49 in the vicinity of Moss Landing (7%). 157 reported incidents (24%) occurred in the City of Monterey and 135 incidents (30%) occurred in the City of Salinas. Additionally, over this 5-year timeframe hazardous material releases have been related to 40 injuries, 16 fatalities, and 23 evacuations. Further historical hazardous material spill report data is available on the Cal OES website.
11.2.2 LOCATION
The following locations have the potential of hazardous materials releases:
• Business and Industrial Facilities: Retail, manufacturing and light industrial firms are areas of concern. These facilities have the highest concentration of hazardous materials at fixed facilities in the planning area due to their manufacturing operations. Anhydrous ammonia and chlorine gas are the two most common extremely hazardous substances used in Monterey County. These materials are used primarily for cold storage by the produce industry, drinking water and wastewater treatment, and water treatment and cooling for pre-cut salad processing. It is anticipated that a release occurring at these businesses would present the greatest likelihood of having an off-site consequence and could have a major impact on the surrounding areas. In addition to these types of businesses, there are several large agricultural chemical wholesalers and applicators that handle large quantities of various pesticides. Another business that may present significant hazards because of the types and quantities of chemicals handled and the proximity to populated areas would include electric power generating facilities.
Approximately 90 businesses have been identified under the California Accidental Release Prevention (CalARP) program as handling and storing a regulated hazardous substance in quantities above the California recognized threshold quantities. • Agricultural Areas: Accidental releases of pesticides, fertilizers, and other agricultural chemicals may be harmful to both humans and the environment. Monterey’s agricultural industry is a heavy user of pesticides and fertilizers, and the incorrect production and storage of these chemicals can only contaminate the soil, air, and water, and can cause a fire or an explosion. Agricultural pesticides are transported daily in and around the County.
• Harbors: Harbors are a potential location for hazardous materials spills. Marine tank vessels and refined petroleum products such as gasoline, diesel and bunker fuel used by ships are sources of potential oil spills. The Monterey and Moss Landing Harbors are potential locations for hazardous materials incidents.
• Illegal Drug Operations: Illegal operations such as laboratories for methamphetamine can pose a threat. Laboratory residues are often dumped along roadways or left in rented hotel rooms, creating a serious health threat to unsuspecting individuals and to the environment.
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• Illegal Dumping Sites: Hazardous wastes such as used motor oil, solvents, or paint are occasionally dumped in remote areas or along roadways, creating a potential health threat to unsuspecting individuals and to the environment. • Transportation Routes: The County’s transportation system consists of a network of federal, state, and county roads, airports, and rail service that all have the potential for hazardous material incidents. The trucks and trains that use these transportation corridors commonly carry a variety of hazardous materials, including gasoline, other crude oil derivatives, and other chemicals known to cause human health problems.
Major transportation routes in the County include:
o US 101, State Route 1 (Highway 1), State Route 156, State Route 183, State Route 68, State Route 198, and County Routes G14, G15, and G18 o Amtrak long distance and intercity trains through the County o Railroad lines
o General Aviation Airports
• Pipelines: This information is provided by the National Pipeline Mapping System and is available to general public. Information does indicate that several pipelines conveying gas or hazardous liquids cross the County.
• Oil Fields: The County’s active oil fields are subject to fire or explosion. The San Ardo Oil Fields are a possible location of a hazardous materials incident.
DTSC Hazardous Waste and Substances Site List (as of May 13, 2021), lists 110 sites in Monterey County with potential to release hazardous materials. Additionally, two sites in Monterey County are currently listed by the EPA on the Federal Superfund National Priorities List (NPL):
Crazy Horse Sanitary Landfill
The Crazy Horse Sanitary Landfill site is a 125-acre sanitary landfill in Salinas, California. A landfill has operated on site since 1950. The landfill is owned by the City of Salinas and operated by Salinas Disposal Services. The facility receives about 162,000 tons of refuse a year.
Landfill operations contaminated groundwater with hazardous chemicals. Following initial actions to protect human health and the environment, EPA is evaluating whether additional cleanup measures are needed.
Fort Ord
The 27,827-acre Fort Ord site was established in 1917 by the US Army as a maneuver area and field artillery target range. In 1991, Fort Ord was selected for decommissioning, but the post did not formally close until 1994. Prior to closing in September 1994, the base's primary mission was training infantry military personnel. The EPA placed the site on the Superfund program’s National Priorities List (NPL) in 1990. The site contained leaking petroleum underground storage tanks, a 150-acre landfill used to dispose of residential waste and small amounts of commercial waste generated by the base, a former fire drill area, motor pool maintenance areas, small dumpsites, small arms target ranges, an 8,000-acre firing range and other limited areas that pose threats from unexploded ordnance.
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On November 20, 2020, the EPA published a Federal Register notice announcing its proposal to remove 11,934 acres of the 27,827-acre Fort Ord Superfund site from the NPL. This deletion is a “partial deletion” (meaning it includes only a part of the cleanup at a portion of the site where cleanup is finished); and only covers cleanup work for military munitions and soil pollution. EPA and the State of California will continue to oversee the US Army’s cleanup at the rest of the site.
The Army is the lead federal agency for the cleanup. The Army will continue to clean up the groundwater and soil gas on the 11,934 acres. It will also cleanup all pollution at the remaining 15,893 acres of the site. Both the groundwater and soil cleanup for the 11,934 acres and the entirety of the 15,893 acres are still in the Superfund program.
11.2.3 FREQUENCY
Hazardous material incidents may occur at any time in the County, given the presence of transportation routes dividing the County, the location of businesses and industry that use hazardous materials, the presence of scattered illegitimate businesses such as clandestine drug laboratories, and the improper disposal of hazardous waste. Based on previous occurrences (as noted above 667 incidents occurred over a 5-year period), Monterey County can expect small hazardous material incidents to occur many times a year. The likelihood of a significant hazardous materials release within the County is more limited and difficult to predict but is assumed to be highly likely.
11.2.4 SEVERITY
Hazardous materials come in the form of explosives, flammable and combustible substances, poisons, and radioactive materials. Hazards can occur during production, storage, transportation, use or disposal. The release or spill of hazardous materials requires a different response depending on factors such as the amount, type, and location of the spill. Each location should have its own specific cleanup procedure, and all personnel handling such material should have received instruction on that procedure. The speed of onset of a hazardous materials spill is generally short. The duration is typically short as well, though certain chemicals can pollute earth and groundwater for long periods of time. Comprehensive information on the probability and magnitude of a hazardous material event is not available. Wide variations among the characteristics of hazardous material sources and among the materials themselves make such an evaluation difficult.
11.2.5 WARNING TIME
Hazardous material incidents occur without predictability under circumstances that give responders little time to prepare.
11.3 SECONDARY HAZARDS
Roadway or railroad closures due to a transportation-related hazardous material spill would have serious effects on the local economy and ability to provide services. Loss of major travel Packet Page 383
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routes would result in loss of commerce and could impact the ability to provide emergency services to citizens. The ability to receive fuel deliveries could be impacted. It is also common to see hazardous materials releases as escalating incidents resulting from other hazards such as floods, wildfires, and earthquakes. The release of hazardous materials can greatly complicate or even eclipse the response to the natural hazards disaster that caused the spill.
11.4 RISK ASSESSMENT
To assess hazardous materials incident risk, buffer distances were used. The chosen buffer distance was based on guidelines in the US Department of Transportation’s Emergency Response Guidebook that suggests distances useful to protect people from vapors resulting from spills involving dangerous and toxic substances. The recommended buffer distance, or “protective action distance” is the area surrounding the incident in which people are at risk of harmful exposure. For this plan, a buffer distance of one mile was used, but actual buffer distances will vary depending on the nature and quantity of the release, whether the release occurred during the night or daytime, and prevailing weather conditions.
To analyze the risk in the County to a transportation-related hazardous materials release, a one-mile buffer was applied to highways in the US Dept of Transportation, National Transportation Atlas Database. The result is a two-mile buffer zone around each transportation corridor that is used for this analysis. Risk from a fixed facility hazardous materials release was analyzed using a one-mile buffer applied to facilities identified in the Monterey County 2019 Hazardous Materials Plan.
11.4.1 POPULATION
As seen in Table 11-3, close to 250,000 people could be exposed to mobile source hazardous materials incidents, and a little over 100,000 people could be exposed to a fixed source hazardous materials incident.
Table 11-3: Population Exposed to Hazardous Materials Incident Risk Table 11-3
Population Exposed to Hazardous Materials Incident Risk in Monterey County Supervisorial District Mobile Source Fixed Source
District 1 43,569 46,909
District 2 41,632 15,718
District 3 64,443 35,240
District 4 58,962 16,439
District 5 40,379 2,956
Total 248,985 117,262
Variables affecting exposure in the event of a hazardous materials incident include the type of product, the physical and chemical properties of the substance, the physical state of the product, the ambient temperature, wind speed, wind direction, barometric pressure, and Packet Page 384
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humidity. With so many variables, true population exposure numbers are difficult to determine.
In general, those who live near transportation corridors or businesses with hazardous materials are more at risk; but each chemical incident is different, and the scenarios are numerous.
Hazardous materials pose a significant risk to emergency response personnel. All potential first responders and follow-on emergency personnel in the County currently are and will be properly trained to the level of emergency response actions required of their individual position at the response scene. Hazardous materials incidents can also pose a serious long-term threat to public health, and those who already are at high risk of health complications, the young, and the elderly, may be more vulnerable to health impacts.
11.4.2 PROPERTY
During a hazardous materials transportation spill, it is generally people that are at risk to the effects of the spill. During a spill, buildings, property, and their values are at a lesser risk; however, given the location of hazardous materials in the County, an analysis is performed here.
Table 11-4 and Table 11-5 summarizes property that is exposed to hazardous material incident risk from fixed and mobile source.
Table 11-4: Residential Property Exposed to Hazardous Materials Incident Risk Table 11-4
Residential Property Exposed to Hazardous Materials Incident Risk in Monterey County Supervisorial
District
Mobile Source Fixed Source
# Value # Value
District 1 5,374 $2,014,276,564 5,348 $1,709,901,633
District 2 7,762 $3,094,087,641 1,400 $529,147,582
District 3 8,823 $2,722,732,839 5,114 $1,607,471,282
District 4 11,156 $5,267,765,844 3,512 $1,511,657,663
District 5 12,968 $14,243,375,574 526 $327,493,551
Total 46,083 $27,342,238,462 15,900 $5,685,671,711
Table 11-5: Non-Residential Property Exposed to Hazardous Materials Incident Risk Table 11-5
Non-Residential Property Exposed to Hazardous Materials Incident Risk in Monterey County Supervisorial
District
Mobile Source Fixed Source
# Value # Value
District 1 3,969 $1,574,141,766 3,170 $1,315,727,602
District 2 5,299 $1,581,922,328 1,218 $575,693,618
District 3 5,047 $3,361,071,791 2,978 $1,866,871,670
District 4 5,799 $2,233,416,936 1,878 $675,704,517
District 5 7,444 $3,435,240,541 180 $36,676,356
Total 27,558 $12,185,793,362 9,424 $4,470,673,763
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11.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
Hazardous materials may be stored at or transported along critical facilities. These facilities are susceptible to accidents and are visible targets for terrorism. The impact of a hazardous material spill or transportation incident will likely be localized to the particular facility, hospital, port, airport, railroad, road, highway, or interstate. The potential losses vary because of the variable nature of the hazardous material spill, but costs from product loss, property damage and decontamination and other costs can add up to millions of dollars. Critical infrastructure exposed to hazardous materials risk is summarized in Table 11-6.
Table 11-6: Critical Infrastructure Exposed to Hazardous Materials Incident Risk Table 11-6
Critical Infrastructure Exposed to Hazardous Materials Incident Risk in Monterey County Critical Infrastructure Type Mobile Source Fixed Source Facilities
Emergency Response 36 11
Fire Station 32 9
Police Station 0 5
Medical Facilities 0 22
Military Facility 3 0
Large Public Facilities 3 1
Educational Facilities 119 48
Power Plant 1 0
Water & Wastewater Facilities 233 61
Stormwater Facilities 4 6
Government Facilities 151 103
Communication Facilities 890 335
Rain Gauges 12 2
Lighthouses 1 0
Dams 0 0
Hazardous Materials
Active or Idle Oil Well 1522 20
Landfill 0 1
Underground Tank 121 -
Cal ARP Facility 72 -
Transportation
Airport 5 2
Bridge 52 12
Harbor 1 0
Highway/Freeway (Miles) - 73
Driveway (Miles) - 0
Major Road (Miles) - 133
Local (Miles) - 283
Railroad (Miles) - 23
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11.4.4 ENVIRONMENT
The risk of hazardous material spills to the environment is considerable. Hazardous materials spilled along roads or railways can pollute rivers, streams, wetlands, riparian areas, and adjoining fields. Other hazardous materials released into the air can severely impact plant and animal species. Reducing risk exposure to the built environment will also mitigate potential losses to the natural environment.
Depending on the characteristic of the hazardous material or the volume of product involved, the affected area can be as small as a room in a building or as large as many square miles that require soil remediation. More widespread effects occur when a product contaminates the municipal water supply or water system such as a port, river, lake, or aquifer. Such environmental damage can linger for decades.
11.4.5 ECONOMIC IMPACT
Hazardous materials incidents in Monterey County have the potential to impact many important economic sectors. Large hazardous material spills can drive away tourists. Hazardous materials incidents could impact the agricultural industry, which could have large economic implications.
11.5 FUTURE TRENDS IN DEVELOPMENT
The number and types of hazardous chemicals stored in and transported through the County will likely continue to increase. As population grows, the number of people vulnerable to the impacts of hazardous materials spills will increase. Development will continue to happen within hazardous materials incident risk zones.
Population and business growth along major transportation corridors increases the vulnerability to transportation-related hazardous material spills. Those who choose to develop in these areas should be made aware of the risks associated with living within close proximity to hazardous materials risk.
11.6 ISSUES
Key issues associated with hazardous materials incidents in Monterey County include:
• Train first responders and all appropriate local government staff to implement protocols contained in the Monterey County Hazardous Materials Plan. • Anhydrous ammonia and chlorine gas, two chemicals commonly used in industrial processing in Monterey County are anticipated to present the greatest likelihood of having an off-site consequence and could have a major impact on the surrounding areas. The County should continue to monitor and regulate the use of these chemicals. • Power generating facilities present a hazardous materials release risk.
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• Accidental releases of pesticides, fertilizers, and other agricultural chemicals are a concern due to their potential to have harmful effects on both humans and the environment. • Work proactively with hazardous materials facilities to follow best management practices:
o Placards and labeling of containers
o Emergency plans and coordination
o Standardized response procedures
o Notification of the types of materials being transported through the County at least annually
o Random inspections of transporters as allowed by each company o Installation of mitigating techniques along critical locations o Routine hazard communication initiatives
o Consideration of using alternative products that are safer Packet Page 388
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12. HUMAN-CAUSED HAZARDS
12.1 OVERVIEW
Although the Disaster Mitigation Act does not require an assessment of human-caused hazards, the Monterey County Steering Committee decided to include human-caused hazards in this hazard mitigation plan for the following reasons:
• Monterey County takes a proactive approach to disaster preparedness in order to protect the public safety of all citizens.
• Preparation for and response to a human-caused disaster involves much of the same staff, training, critical decision making, and commitment of resources as a natural hazard.
• The multi-hazard mitigation planning effort is an opportunity to inform the public about all hazards, including human-caused hazards.
• The likelihood of a human-caused hazard event in the County is greater than that of several of the natural hazards identified in this Plan. • During public outreach events, many community members expressed concern for increasing amounts of human-caused hazards.
The following human-caused hazards discussed in this plan: Cyber-Attack, Targeted Violence, Terrorism, and Mass Migration.
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12.1.1 CYBER-ATTACK
A cyber-attack 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 information technology continues to grow in capability and interconnectivity, cyber-attacks become increasingly frequent and destructive.
Types of Cyber-Attacks
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 combat. 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 proprietary, protected, or confidential information. The spectrum of cyber-risks is limitless, with threats having a wide range of effects on the individual, community, and all private and public organizations. This risk assessment includes cyber-attacks and cyber-terrorism under the inclusive hazard of cyber-threats. The terms often are used interchangeably, though they are not the same. While all cyber-terrorism is a form of cyber-attack, not all cyber-attacks are cyber-terrorism.
Public and private computer systems can experience a variety of cyber-attacks, from blanket malware infection to targeted attacks on system capabilities. Cyber-attacks specifically seek to breach Information Technology (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 different types of attacks that can be automated or targeted.
Ransomware Attacks
Ransomware attacks, a type of cyber-attack, is becoming increasingly common against individuals, small- and medium-sized organizations, utilities, and local governments. Cyber ransom occurs when an individual downloads ransom malware, or ransomware, often through phishing, 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. Cyber-attacks often target government networks to gain access to sensitive personal information of citizens and employees, as well as proprietary software, strategic plans, and other information.
Prior to the COVID-19 pandemic, state and local governments were already plagued by cybersecurity threats. Ransomware attacks, in which the attacker encrypts a system and demands money to unlock it, have increasingly impacted government entities across the nation over the past two years.
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Cyber-Terrorism
Cyber-terrorism 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, cyber-terrorism seeks to evoke strong emotional reactions, but it does so through information technology rather than a physically violent or disruptive action. Cyber-terrorism has three main types of objectives:
• Organizational: Cyber-terrorism 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, fundraising, communication, or planning. Organizational cyber-terrorism 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: Cyber-terrorism 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.
• Destructive: The destructive objective for cyber-terrorism is what organizations fear most. Through the use of computer technology and the Internet, terrorists seek to inflict destruction or damage on tangible property or assets, and death or injury to individuals.
12.1.2 TARGETED VIOLENCE
Targeted violence refers to any incident of violence in which an attacker selects a particular target prior to the violent attack. Unlike terrorism, targeted violence includes attacks otherwise lacking a clearly discernible political, ideological, or religious motivation, but that are of such severity and magnitude as to suggest an intent to inflict a degree of mass injury, destruction, or death commensurate with known terrorist tactics. Targeted violence has a significant impact on the safety and security of communities, schools, places of worship, and other public gatherings.
The threats of terrorism and targeted violence increasingly intersect with one another.
Active shooter attacks are typically motivated by the desire to maximize human casualties. They are differentiated from other attack types by the indiscriminate nature of the victim’s targets of opportunity rather than actions directed toward a specific target. Active shooter attacks have evolved over the last decade ranging from “lone wolf” shooters who act alone and without any organizational affiliation to organized groups acting in concert to achieve a specific objective.
An active shooter is an individual actively engaged in killing or attempting to kill people in a confined and populated area; in most cases, active shooters use firearms and there is no Packet Page 391
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pattern or method to their selection of victims. Active shooter situations are unpredictable and evolve quickly. Typically, the immediate deployment of law enforcement is required to stop the shooting and mitigate harm to victims. Active shooter situations are often over within 10 to 15 minutes, before law enforcement arrives on the scene.
12.1.3 TERRORISM
Terrorism is defined in the Code of Federal Regulations as “the unlawful use of force and violence against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives” (28 CFR, Section 0.85). The FBI categorizes two types of terrorism in the US:
• Domestic terrorism involves groups or individuals without foreign direction whose terrorist activities, including the use of WMDs, are directed at the government or population. The FBI, the primary response agency for domestic terrorism, coordinates domestic preparedness programs and activities to limit domestic terrorism. • International terrorism involves groups or individuals whose terrorist activities are foreign-based and/or directed by countries or groups outside the United States, or whose activities transcend national boundaries.
Terrorism can be perpetrated through several methods including Weapons of Mass Destruction (WMD), which includes biological, chemical, nuclear, and radiological weapons; arson, incendiary, explosive, and armed attacks; industrial sabotage and intentional hazardous materials releases; agriterrorism; and “cyber-terrorism.” Within these general categories, however, there are many variations. Particularly in the area of biological and chemical weapons, there are a wide variety of agents and ways for them to be disseminated. Table 12-1 provides a hazard profile summary for terrorism-related hazards.
Table 12-1: Event Profiles for Terrorism
Table 12-1
Event Profiles for Terrorism
Hazard Application
Mode
Hazard Duration/ Extent Mitigating and Exacerbating
Conditions
Conventional
Bomb/
Improvised
Explosive
Device
Detonation of
explosive device
on or near target;
delivery via
person, vehicle,
or projectile.
Instantaneous; additional
"secondary devices" may be
used, lengthening the time
duration of the hazard.
Extent of damage is
determined by type and
quantity of explosive. Effects
generally static other than
cascading consequences,
incremental structural
failure.
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, structures, etc.
can provide shielding by absorbing
and/or deflecting energy/debris.
Exacerbating conditions: ease of
access to target; lack of shielding;
poor construction; ease of device
concealment.
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Table 12-1
Event Profiles for Terrorism
Hazard Application
Mode
Hazard Duration/ Extent Mitigating and Exacerbating
Conditions
Chemical
Agent
Liquid/aerosol
contaminants
dispersed using
sprayers or other
aerosol
generators;
liquids vaporizing
from puddles/
containers; or
munitions.
Chemical agents may pose
viable threats for hours to
weeks depending on the
agent and the conditions in
which it exists.
Contamination can be
carried out of the initial
target area by persons,
vehicles, water, and wind.
Chemicals may be corrosive
or otherwise damaging over
time if not remediated.
Air temperature affects evaporation
of aerosols. Ground temperature
affects evaporation of liquids.
Humidity can enlarge aerosol
particles, reducing inhalation hazard.
Precipitation can dilute but also
spread agent. Wind can disperse
vapors but cause target area to be
dynamic. Micro-meteorological
effects of buildings/terrain can alter
travel and duration of agents.
Sheltering in place can protect people
from harmful effects.
Arson/
Incendiary
Attack
Initiation of fire
or explosion on
or near target via
direct contact or
remotely via
projectile.
Generally, minutes to hours.
Extent of damage
determined by type and
quantity of device,
accelerant, and materials
present at or near target.
Mitigation factors include built-in fire
detection and protection systems and
fire-resistive construction. Inadequate
security can allow easy access to
target and easy concealment of
incendiary device. Noncompliance
with fire and building codes, as well as
failure to maintain existing fire
protection systems, can increase the
effectiveness of a fire weapon.
Armed Attack Tactical assault or
random attack.
Generally, minutes to days.
Extent varies based on
perpetrators’ intent and
capabilities.
Inadequate security can allow easy
access to target, easy weapons
concealment, and undetected
initiation of attack.
Biological
Agent
Liquid or solid
contaminants
dispersed using
aerosols or by
point or line
sources such as
munitions, covert
deposits, moving
sprayers.
Hours to years, depending
on the agent and the
conditions in which it exists.
Depending on the agent
used and the effectiveness
of deployment, agent can
spread via wind and water.
Infection can spread via
humans or animals.
Altitude of release above ground can
affect dispersion; sunlight is
destructive to many bacteria and
viruses; light to moderate wind will
disperse agents but higher winds can
break up aerosol clouds; the micrometeorological effects of buildings and terrain can influence
aerosolization and travel of agents.
CyberTerrorism
Electronic attack,
one computer
against another.
Minutes to days. Generally,
no direct effects on built
environment.
Inadequate security can allow access
to critical computer systems, letting
them to be used to conduct attacks.
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Table 12-1
Event Profiles for Terrorism
Hazard Application
Mode
Hazard Duration/ Extent Mitigating and Exacerbating
Conditions
Agriterrorism
Direct, covert
contamination of
food supplies or
introduction of
pests or disease
agents to crops
and livestock.
Days to months. Extent
varies by type of incident.
Food contamination may be
limited to specific sites,
while pests and diseases
may spread widely.
Inadequate security can facilitate
adulteration of food and introduction
of pests and disease agents to crops
and livestock.
Radiological
Agent
Radioactive
contaminants
dispersed using
sprayers/ aerosol
generators, or by
point or line
sources.
Seconds to years, depending
on material used. Initial
effects will be localized to
site of attack; based on
climatic conditions,
successive behavior of
material may be dynamic.
Duration of exposure, distance from
source of radiation, and the amount
of shielding between source and
target determine exposure to
radiation
Nuclear
Bomb
Detonation of
nuclear device
underground, at
the surface, in
the air, or at high
altitude.
Light/heat flash and
blast/shock wave last
seconds; nuclear radiation
and fallout can persist for
years. Initial blast effects of a
subsurface, ground or air
burst are static, determined
by device’s characteristics/
employment; fallout of
radioactive contaminants
may be dynamic.
Harmful effects of radiation can be
reduced by minimizing the time of
exposure. Light, heat, and blast
energy decrease logarithmically as a
function of distance from seat of
blast. Terrain, forestation, structures,
etc. can provide shielding by
absorbing and/or deflecting radiation
and radioactive contaminants.
Intentional
Hazardous
Material
Release
Solid, liquid,
and/or gaseous
contaminants
released from
fixed or mobile
containers
Hours to days. Chemicals
may be corrosive or
otherwise damaging over
time. Explosion and/or fire
may be subsequent.
Contamination may be
carried out of the incident
area by persons, vehicles,
water, and wind.
Weather conditions directly affect
how the hazard develops. The micrometeorological effects of buildings and terrain can alter travel and
duration of agents. 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.
Source: FEMA 386-7, State and Local Mitigation Planning How-To Guide: Integrating Manmade Hazards Packet Page 394
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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 train to respond not only to organized terrorism events, but also to random acts by individuals who, for a variety of reasons ranging from fear to emotional trauma to mental instability, 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.
12.1.4 MASS MIGRATION
Population migration of large scales can lead to resource pressure - such resources include water, gasoline, housing, transportation, first responders, medical care, government services - on communities receiving the migrants and can exacerbate existing instability. In communities lacking the capacity to manage a rapid influx or exodus or already managing underlying threats, migration of this scale greatly increases the potential to destabilize communities. Types of mass migration include large gatherings, planned events, tourism, migrant agriculture, and permanent retreats from hazard impacted areas.
Large Gatherings/ Special Events
Large gatherings refer to a planned or spontaneous event, indoors or outdoors, with a significant number of people participating or in attendance such as a community event or gathering, concert, festival, conference, parade, wedding, protests, or sporting event.
Special events result in concentrations of large numbers of people in limited geographic areas.
Such concentrations exacerbate the effects of any other hazard that may result from or be coincidental to the event. Special events may increase the likelihood of human-caused hazards such as terrorism, civil unrest or high-occupancy building fires. Injuries and/or loss of life may be much greater if naturally occurring hazards such as earthquakes or adverse weather occur during a special event. Simply having a massive concentration of people requires additional planning and caution, regardless of the special risks associated with any particular event. Largescale special events require the deployment of police, fire, and emergency medical personnel, rendering these resources unavailable for response to emergencies in other locations in the community. Many large-scale special events result in street closures and increased traffic congestion, slowing response time for emergency personnel and equipment.
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Transient and Non-Resident Populations
The physical location and the geographic terrain of Monterey County has created a nexus for several economic drivers which attract transient, non-resident populations. In Monterey County, the Agriculture and Tourism sectors experience seasonal fluctuations, and subsequently an ongoing high rate of population influx and outflow.
A migrant farmworker is defined as an individual who is required to be absent from a permanent place of residence for the purpose of seeking employment in agricultural work. Due to the seasonal nature of agriculture, workers travel and work throughout the US, serving as the backbone for this major industry. The National Agricultural Workers Survey (NAWS) defines a migrant farmworker as a person who reported jobs that were at least 75 miles apart or who reported moving more than 75 miles to obtain a farm job during a 12-month period. While the vast majority of farmworkers in the US are settled (81%), around 19% are migratory. 35 California growers employ one out of three of the nation’s farmworkers. Annual influxes of agricultural workers can place a strain on local resources.
Over the past decades, global tourism industry has been growing exponentially, more than doubling between 1992 and 2012. By 2030, annual international tourism is estimated to grow to up to 1.8 billion.36 Therefore, tourism is becoming globally one of the most important economic activities, at the same time, the sector is regularly challenged by crises caused by natural, man-made or other often subjective risks. Risks associated with the tourism industry include:
• Tourism infrastructure is often located in areas exposed to sudden-onset natural disasters, in particular beach and coastal areas, river valleys and mountain regions. • Many natural disasters, crime incidents, epidemics, acts of terrorism and civil strife are either deliberately targeted at places where tourists gather or coincidentally occur in areas with high concentrations of tourists.
• Tourists often lack familiarity with a destination region, local customs, language, or a lack of awareness of local security risks and threats often result in the tourists having a higher propensity to find themselves in dangerous situations than many local residents. • As seen during the COVID-19 Pandemic, tourism has also been a significant contributing factor in the rapid spread of infectious diseases.
• A large-scale disaster is likely to stretch the capacity of emergency services in any jurisdiction, but large tourist populations can further strain the capabilities of medical, emergency rescue, police, ambulance, and hospital services to cope with a disaster. • While residents are normally easy to locate and identify by local emergency agencies, tourists by virtue of their transient presence are not. 35 Findings from the National Agricultural Workers Survey (NAWS) 2015-2016: A Demographic and Employment Profile of United States Farmworkers. JBS International (January 2018). 36 Tourism and Disaster Risk. UN World Conference on Disaster Risk Reduction (2015) Packet Page 396
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Retreat from Hazard Impacted Areas
One of the most pressing concerns relates to the growth in climate-induced migration. In 2017,
68.5 million people were forcibly displaced, more than at any point in human history. While it is difficult to estimate, approximately one-third of these (22.5 million to 24 million people) were forced to move by “sudden onset” weather events, such as flooding, wildfires, and intensified storms.37 While the remaining two-thirds of displacements are the results of other crises, it is becoming apparent that climate change is contributing to so-called slow onset events such as desertification, sea-level rise, ocean acidification, air pollution, rain pattern shifts and loss of biodiversity. Put simply, climate change will cause population movements by making certain parts of the world much less viable places to live; by causing food and water supplies to become more unreliable and increasing the frequency and severity of floods and storms. Migration is possibly the most direct adaptation strategy to climate change. As climate change continues with tremendous changes in local living conditions, populations in communities with worsening conditions consider moving to better places, provided the costs of migration are affordable.
Additionally, sudden climatic changes or natural disasters might lead, in the absence of alternatives, to migration choices which are forced rather than the result of a well-planned process.
Evidence of sudden disaster-induced displacement can be found after catastrophic Camp Fire in 2018. The wildfire destroyed over 18,000 structures and led to the temporary displacement of approximately 56,000 residents and the longer-term displacement of over 20,000 residents.
The majority of long-term displaced residents fled the Town of Paradise, where nearly 95% of the community’s structures were damaged and destroyed. The sudden influx of people across the region for an extended period of time put a strain on the resources of municipalities surrounding the burn scar. In 2019, the City of Chico estimated more than $500 million in impacts associated with sudden growth and pressure on local infrastructure. The impacts of the Camp Fire have substantially changed the dynamics of growth in the region, with some communities, like the City of Chico, experiencing more than a decade worth of growth in one year. Meanwhile, the Town of Paradise experienced a population loss of about 83% from 2018 to 2019 and Butte County saw a loss of more than 10,000 residents between 2019 and 2020. It will likely take at least two decades for the Town of Paradise to approach its former population, but the level of losses means the community will never be made whole. Many former residents of both Paradise and Butte County are likely to never return. Understanding how many of these residents may return in the future will require more extensive research and outreach, but interviews and surveys conducted as part of the Town of Paradise Recovery Plan revealed between that about 25% and 35% were looking to return in the future. 38 37 The climate crisis, migration, and refugees. John Podesta, The Brookings Institute (July 25, 2019). 38 The Impacts of Camp Fire Disaster on Housing Market Conditions and Housing Opportunities in the Tri-County Region. Peloton Research + Economics (September 1, 2020) Packet Page 397
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12.2 HAZARD PROFILE
12.2.1 HISTORY
Cyber-Attack
The County has experienced a number of coordinated attacks over recent years. In 2015, one large County department was hit by the CryptoWall ransomware as a result of a user downloading an infected file. Over 1,500 shared files were encrypted, became unrecoverable, and had to be restored from backup.
Another ransomware incident occurred in 2020, when an attacker successfully broke into and planted the “CrySIS” ransomware variant on a file server in one of the County’s newly merged departments. A ransom note asking for $10,000 was left behind. The ransomware encrypted all shared files on the department’s file server, effectively destroying years of work. The technology for this new department has since been upgraded and brought up to County standards.
On a monthly basis, the County is hit by credential stealing attacks. In these attacks, an enduser surrenders their Office365 credentials to an attacker, usually through a phishing attack.
The attacker then logs into Office365 remotely, sets up automated Outlook rules so that the victim cannot see any replies to the emails sent from this account, and then proceeds to use the account to trick other County users into surrendering their credentials as well. The goal of the attacker in these cases is most likely financial gain through the sales of the credentials, spamming, and potential theft of information. This can be mitigated through the deployment of user-friendly two-factor authentication.
Targeted Violence
In the US, between 2000 to 2018 there were 277 active shooter incidents and 2,430 casualties, including 884 killed and 1,546 wounded. 39 In the neighboring jurisdiction of Santa Clara County, a mass shooting occurred at the Gilroy Garlic Festival in Gilroy, California, on July 28, 2019. The gunman killed himself and three others and wounded 17 people. The FBI opened a domestic terrorism investigation into the incident.
Terrorism
In May and June 2020 multiple attacks were made on federal and local law enforcement in Oakland and Ben Lomond, California. The actors were affiliated with the Boogaloo Movement, known for its extremist, anti-law enforcement views and ties to a movement that believes a second American Civil War is coming soon. The actors are accused of assassinating a Federal Protective Services Officer and injuring his partner on the night of May 29, after firing on them 39 Quick Look: 277 Active Shooter Incidents in the United States From 2000 to 2018, Federal Bureau of Investigations Office of Partner Engagements
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from a white van, in what is described as “an ambush.” The actors purposefully chose the night of massive protests to gain cover for the attacks.
On June 6, 2020, Santa Cruz deputies responded to a call about a suspicious van parked off the road. The caller saw guns and bomb-making materials inside the van, according to the sheriff’s department. The actor would later lob pipe bombs and open fire with assault weapons on law enforcement officers in Ben Lomond, killing one Santa Cruz deputy and injuring two other Santa Cruz deputies.
Mass Migration
An influx of agricultural workers to the Salinas and Pajaro Valleys occurs every year during peak growing season. For the three-year period 2014-16, the average monthly employment in the region reached 80,715 during July. The month of the lowest total, with 34,737 employed, was January, reflecting the seasonal pattern of agriculture sector jobs. The three-year annual average of monthly employment in the region increased from 49,035 during 2005-07 to 60,837 during 2014-16. Thus, annual average agricultural employment in the Salinas-Pajaro Valleys increased by a remarkable 24% during the past decade. 40 Monterey County has more farmworkers per acre than any other county in the nation; half of those laborers will come from outside the county. The seasonal increase of migratory agricultural workers during the peak of the 2020 COVID-19 pandemic provided significant challenges for reducing the spread of COVID-19 and protecting vulnerable populations.
Monterey County receives 4.6 million visitors a year and hosts approximately 50 large events per year, therefore large population influxes of tourists and event attendees have historically happened regularly in the County.
12.2.2 LOCATION
Cyber-Attack
This hazard is not geographically based. Attacks can originate from any computer to affect any other computer in the world. If a system is connected to the Internet or operating on a wireless frequency, it is susceptible to exploitation. An international study released by Malwarebytes in 2016 found that 46% of all ransomware attacks originated from email. 41 Targets of cyber-attacks can be individual computers, networks, organizations, business sectors, or governments. Financial institutions and retailers are often targeted to extract personal and financial data that can be used to steal money from individuals and banks. The most affected sectors are finance, energy and utilities, and defense and aerospace, as well as communication, retail, and health care. Both public and private operations in Monterey County are threatened 40 Farmworker Housing Study and Action Plan for Salinas Valley and Pajaro Valley, California Institute for Rural Studies (April 2018) 41 Understanding the Depth of the Global Ransomware Problem, Malwarebytes (August 2016) Packet Page 399
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on a near-daily basis by millions of currently existing cyber-attacks developed to automatically seek technological vulnerabilities.
Targeted Violence
Active shooter incidents typically occur at the following locations: areas of commerce - 43.7%; educational environments - 20.6%; government property - 9.4%; open spaces - 13.4%; residences - 4.3%; houses of worship - 4%; health care facilities - 4.3%; and other location -
0.4%. 42
Terrorism
Monterey County has identified numerous high-profile targets for potential terrorists. Large population centers, high visibility tourist attractions, and critical infrastructure accessible to the public present security challenges of an ongoing nature in the County.
Some key assets considered as locations for terrorist attacks in Monterey County include:
• Government Offices • Military Installations
• Emergency Services • Politically or symbolically significant sites • Transportation infrastructure • Energy, water, and related utility systems • Health care system • Telecommunications and information systems • Agricultural facilities • Mobile assets
• Recreational facilities • Events and attractions
Mass Migration
The mass migration of agricultural workers is likely to affect the Salinas and Pajaro Valleys and cities along the Highway 101 corridor.
Large events in Monterey County include the AT&T Pebble Beach Pro-Am, the Sea Otter Classic, the California International Air Show, the Big Sur International Marathon, the Big Sur Food & Wine Festival, the Firestone Grand Prix, the California Rodeo Salinas, the Sand City West End Celebration, the Artichoke Festival, the Monterey Jazz Festival, and the Concours D'Elegance.
Major tourist attractions are primarily located on the coast and on the densely populated Monterey Peninsula. In 2016, the Monterey County Convention and Visitors Bureau, surveyed approximately 1,300 visitors to the County, both at area lodging properties and specific tourism locations. Based on the 2016 Monterey County Visitor Profile Report Findings, 43major attractions include Cannery Row, Fisherman’s Wharf, the 17-Mile Drive, state parks and beaches, and the Monterey Bay Aquarium. Figure 12-1 shows the percentage visitors who indicated that they had visited or were planning to visit the listed Monterey County attractions. 42 Quick Look: 277 Active Shooter Incidents in the United States From 2000 to 2018, Federal Bureau of Investigations Office of Partner Engagements
43 2016 Monterey County Visitor Profile Final Report of Findings, Monterey County Convention and Visitors Bureau (January 2017)
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Figure 12-1
Monterey County Attractions Visited
Figure 12-1: Monterey County Attractions Visited
Source: Monterey County Convention and Visitors Bureau
The most visited areas of the County are the Cities of Monterey, Pacific Grove, and Carmel-bythe-Sea, and the unincorporated area of Pebble Beach. Figure 12-2 shows the percentage visitors who indicated that they had visited or were planning to visit the listed area.
Figure 12-2
Monterey County Areas Visited
Figure 12-2: Monterey County Areas Visited
Source: Monterey County Convention and Visitors Bureau
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12.2.3 FREQUENCY
Cyber-Attack
Cyber-security threats are experienced on a daily basis, often without being noticed. Up-to-date virus protection software used in the public and private sector prevents most cyber-attacks from becoming successful, but regardless the number of security attacks is increasing. Nearly 80% of US companies have suffered a cyber-attack in the last year and more than half experienced a ransomware incident. 44
State and local governments often struggle with cybersecurity due to limited resources, are often under attack by cyber-criminals and ransomware operators. COVID-19 has increased these challenges. The combination of reduced tax revenues and the additional costs caused by the pandemic are likely to strain budgets reducing expenditures on cybersecurity. This risk is exacerbated by an increasingly decentralized staff. Many employees are still working from home and therefore using their home Wi-Fi network, which is likely less secure than government networks.
Targeted Violence
Studies indicate that the rate at which public mass active shooter incidents occur has tripled since 2011. Between 1982 and 2011, a mass active shooter incident occurred roughly once every 200 days. Between 2011 and 2014 that rate has accelerated greatly with at least one mass shooting occurring every 64 days in the United States. 45 Terrorism
The likelihood of a terrorist event varies with the method of attack, as follows:
• Chemical: The risk of a chemical event is present in the County. The petroleum and agricultural community use and store significant amounts of chemicals that could be used in destructive ways.
• Explosives: The elements necessary to construct a WMD explosive are readily available.
Agricultural communities maintain sufficient products for use in explosive devices. Pipe bomb and suspicious package events have occurred in Monterey County, though none have been specifically identified as a WMD.
• Radiological/Nuclear: The major transportation arteries for vehicles or rail that cross through or near the County contribute to the risk of a radiological event. Such products can pass through any of the regional transportation corridors. • Biological: Anthrax incidents that occurred in the US in October 2001 demonstrate the potential for spreading terror through biological weapons. An agent also could be introduced to livestock, causing harm to public health and the economy. 44 Understanding the Depth of the Global Ransomware Problem, Malwarebytes (August 2016) 45 Rate of Mass Shootings Has Tripled Since 2011, Harvard Research Shows, Amy P. Cohen, Deborah Azrael, and Matthew Miller (October 15, 2014)
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• Combined Hazards: WMD agents can be combined to have a greater total effect. Given the risks associated with chemical agents in Monterey County, the possibility of a combined event exists.
Mass Migration
Mass migration is possible anytime and is likely to occur every year. Mass migration of agricultural workers follows seasonal patterns each year. The peak average monthly employment occurs in July (80,715 average monthly employment from 2014-16) and is at its lowest in January (34,737 average monthly employment from 2014-16). 46 Tourist populations tend to visit the County during the summer months. Monterey County visitors spend an average of 3.6 days and 2.7 nights in the area. 47
12.2.4 SEVERITY
Cyber-Attack
There is no official index for measuring the severity of a cyber-attack. An international study released by Malwarebytes in 2016 found that cyber-ransom threats caused 34% of business victims to lose revenue and 20% had to stop business immediately. The study also reported that nearly 60% of all cyber-ransom attacks demanded over $1,000, over 20% asked for more than $10,000, and 1% asked for over $150,000. 48
Targeted Violence
The severity of targeted violence may vary from a few injured people to multiple injuries and fatalities. A Multiple Casualty Incident (MCI) is defined as any incident with three or more fatalities or critically injuries. MCIs may result from acts of violence such as shootings or hostage situations. Effects may include serious injuries, loss of life, and associated property damage. Because large numbers of patients may be involved, significant MCIs may tax local emergency medical and hospital resources, and therefore require a regional response. First responders, including fire, police, and emergency room staffs at local hospitals, follow established protocols for MCIs. Emergency response mutual aid is requested should local officials be unable to respond appropriately with available personnel and equipment.
Terrorism
The severity of a terrorist attack may vary from a few injured people to multiple injuries and fatalities. Terrorism can also cause the destruction of property, widespread illness and injury, the displacement of large numbers of people, and devastating economic loss. 46 Farmworker Housing Study and Action Plan for Salinas Valley and Pajaro Valley, California Institute for Rural Studies (April 2018)
47 2016 Monterey County Visitor Profile Final Report of Findings, Monterey County Convention and Visitors Bureau (January 2017)
48 Understanding the Depth of the Global Ransomware Problem, Malwarebytes (August 2016) Packet Page 403
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Mass Migration
The severity of mass migration events varies by type of migration and the ability of the location of the migration to absorb the excess population. Mass migration can increase use of limited roadway infrastructure, reduce short-term housing inventory, and increase demand for public safety resources. Mass migration can affect the already limited housing inventory in the County and lead people to live in congested housing. California has severe housing challenges for both rental and homeownership in terms of both supply and affordability. The production of housing has not returned to the level required to meet the projected housing need. 49 The severity of incidents associated at a special event varies greatly but some special events present more risks than others (such as a political rally). It is not uncommon for people to be injured and killed as perpetrators, participants and/or innocent spectators.
12.2.5 WARNING TIME
Cyber-Attack
There is no warning time for cyber-attacks.
Targeted Violence
While active shooter situations are often unpredictable, paying careful attention to warning signs could go a long way in mitigating a potential incident. Some shooters demonstrate progressively escalating risk factors in their mindsets and behaviors that characterize them as violent prior to an attack. Recognizing these warning signs and reaching out for help could bring at-risk individuals to the attention of law enforcement sooner and prevent a future attack.
Potential warning signs 50 include:
• Increasingly erratic, unsafe, or aggressive behaviors. • Hostile behavior based on claims of injustice or perceived wrongdoing. • Drug and alcohol abuse.
• Claims of marginalization or distancing from friends and colleagues. • Changes in performance at work.
• Sudden and dramatic changes in home life or in personality. • Financial difficulties.
• Pending civil or criminal litigation.
• Observable grievances and making statements of retribution.
Terrorism
Warning time for a terrorist attack varies greatly. The Federal Bureau of Investigation (FBI) and the Northern California Regional Intelligence Center (NCRIC) monitor intelligence related to threats of terrorism.
49 California migration: The story of 40 million, CAL MATTERS (July 29, 2019) 50 Active Shooter Attacks: Security Awareness for Soft Targets and Crowded Places, Department of Homeland Security
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Mass Migration
There is no warning time associated with mass migration events. Peak agriculture employment and the tourism season occur during the summer months so the summer season could be considered a time for higher alert to the risk of mass migration. Large events generally have dates identified months in advanced and involve pre-planning efforts, such as permit acquisition, so warning time for the event itself is generally extensive. There is usually no warning time for special events incidents unless a person calls in or posts a specific threat on social media. Then authorities may have a few hours warning time.
12.3 SECONDARY HAZARDS
The following are the most likely secondary hazards associated with human-caused hazards:
Cyber-Attack
Computer security breaches associated with data and telecommunications losses can have significant economic impact. Ransomware attacks on local governments can have wide reaching impacts on services. In the short-term, it can impact emergency response; in the long-term, it can cause a large financial impact on a jurisdiction.
Targeted Violence
An active shooter incident or MCI can make the general public nervous about going out, so that more people stay at home.
Terrorism
The largest secondary impact caused by a terrorist event would be economic. Economic impacts from terrorism could be significant. The cost of a terrorist act would be felt in loss of life and property, disruption of business activity and long-term emotional impacts. Recovery would take significant resources and expense at the local level.
Mass Migration
Mass migration impacts to transportation infrastructure could cause roadway or railroad closures, which would have serious effects on the local economy and ability to provide services.
Loss of major travel routes would result in loss of commerce and could impact the ability to provide emergency services to citizens. The ability to receive fuel deliveries could be impacted.
Mass migration can also have impact on public health and lead to increased crime. The secondary impacts of special events incidents are possible copy-cats deploying the same tactics at an event in their area.
12.4 RISK ASSESSMENT
It is often quite difficult to quantify the potential losses from human-caused hazards. While the facilities themselves have a tangible dollar value, loss from a human-caused hazard often inflicts an even greater toll on a community, both economically and emotionally. The impact to Packet Page 405
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identified values will vary from event to event and depend on the type, location, and nature of a specific incident.
12.4.1 POPULATION
Cyber-Attack
The entire County’s population is exposed to cyber-attacks personally or at places of employment. All populations who directly use a computer or receive services from automated systems are exposed to cyber-terrorism. Because it is difficult to predict the particular target of cyber-terrorism, assessing vulnerability to the hazard is also difficult.
Although all individuals in the County are vulnerable to an attack, certain types of attacks would impact specific segments of the population. If the cyber-attack targeted the County’s power or utility grid, individuals with medical needs would be impacted the greatest. These populations are most vulnerable because many of the life-saving systems they rely on require power. Also, if an attack occurred during months of extreme hot weather, those 65 years of age and older would be vulnerable to the effects of the lack of climate control. These individuals might require an air-conditioned shelter operating on a back-up generator. If a cyber-attack targeted a facility storing or manufacturing hazardous materials, individuals living adjacent to these facilities would be vulnerable to the secondary effects, should the attack successfully cause a critical failure at that facility.
Targeted Violence
A targeted violence event could range from an individual attack to a coordinated attack by multiple agents upon multiple targets. Large-scale incidents have the potential to kill or injure many people in the immediate vicinity and may also affect people a relative distance from the initial event.
Terrorism
A terrorist event could range from an individual attack to a coordinated attack by multiple agents upon multiple targets. Large-scale incidents have the potential to kill or injure many people in the immediate vicinity and may also affect people a relative distance from the initial event. Variables affecting exposure for a WMD attack include the physical and chemical properties of the WMD, the ambient temperature, wind speed, wind direction, barometric pressure, and humidity.
Mass Migration
The entire population of Monterey County could be impacted by a mass migration event, depending on the size and severity.
12.4.2 PROPERTY
Cyber-Attack
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private infrastructure systems. Cyber-attacks can cause physical damage if real assets or end consumers are affected by service disruption. This might occur if cyber-attacks target industries related to utilities, life support, transportation, human services, or telecommunications. In many cases, attacks on these systems initially will not be detected, and any malfunction will be thought to be system failure.
Targeted Violence
All structures in the County are physically vulnerable to a targeted violence event. The emphasis on accessibility, the opportunity for roof access, driveways underneath some structures, unmonitored areas, the proximity of many structures to transportation corridors and underground pipelines, and the potential for an active shooter to strike any structure randomly all have an impact on the vulnerability of structures. Schools, churches, large event venues, and workplaces are known locations of previous targeted violence incidents and are likely more vulnerable to attack.
Terrorism
All structures in the County are physically vulnerable to a terrorism event. The emphasis on accessibility, the opportunity for roof access, driveways underneath some structures, unmonitored areas, the proximity of many structures to transportation corridors and underground pipelines, and the potential for a terrorist to strike any structure randomly all have an impact on the vulnerability of structures.
Mass Migration
Structures are unlikely to be impacted by mass migration events but can restrict an already limited housing inventory in the County, both through increases in population and when housing is taken off the market for the purposes of vacation rental. Congested housing can lead structures to deteriorate faster. Increased use of facilities and visitor-serving amenities are also likely to deteriorate at faster rates when utilized by larger and larger populations.
12.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
Cyber-Attack
All critical facilities and infrastructure that are operated by a computer system are exposed to cyber-attacks. Cyber-attacks may affect structures if any critical electronic systems suffer service disruption. For instance, a cyber-attack may cripple the electronic system that controls a cooling system or pressure system within critical infrastructure. This may result in physical damage to the structure from components overheating, or an explosion if pressure relief systems are rendered inoperable.
Targeted Violence
All critical facilities and infrastructure could be impacted by targeted violence.
Terrorism
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on the two distinct but complementary approaches. First, any given place in the built environment has a certain level of inherent vulnerability that exists independent of any protective or mitigation actions that are applied to it. Second, the security, design, and other mitigation tools used to protect a place determine its tactical vulnerability. 51 The inherent vulnerability of critical infrastructure is based on:
• Visibility: How aware is the public of the existence of the facility, system, or location? • Utility: How valuable is the place in meeting the objective(s) of a potential terrorist? • Accessibility: How accessible is the place to the public? • Asset mobility: Is the asset's location fixed or mobile? If mobile, how often is it moved, relocated, or repositioned?
• Presence of hazardous materials: Are flammable, explosive, biological, chemical, and/or radiological materials present on site?
• Potential for collateral damage: What are the potential consequences for the surrounding area if the asset is attacked or damaged?
• Occupancy: What is the potential for mass casualties based on the maximum number of individuals on site at a given time?
The tactical vulnerability of each critical infrastructure is based on:
• Site Perimeter: Is the facility designed with security in mind—both site-specific and with regard to adjacent land uses? Are vehicle access and parking managed in a way that separates vehicles and structures?
• Building Envelope: Is the building’s envelope designed to be blast-resistant? Does it provide collective protection against chemical, biological, and radiological contaminants?
• Facility Interior: Does security screening cover all public and private areas? Are public and private activities separated? Are critical building systems and activities separated? Are utilities and HVAC systems protected and/or backed up with redundant systems? Are emergency power and telecommunications available? Are alarm systems operational? Is lighting sufficient? Are the building’s water supply and fire suppression systems adequate, code-compliant, and protected? Are on-site personnel trained appropriately? Are local first responders aware of the nature of the operations at the facility? Are systems and personnel in place to monitor and protect the facility? Mass Migration
All critical facilities and infrastructure have the potential to be impacted by mass migration events. In particular, water and road infrastructure capacity could quickly become overwhelmed.
51 FEMA 386-7, State and Local Mitigation Planning How-To Guide: Integrating Manmade Hazards Packet Page 408
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12.4.4 ENVIRONMENT
Cyber-Attack
While effects of cyber-threats on the natural environment are unlikely, they can occur. It would only be through a secondary effect that the environment could be affected by a cyber-attack.
Such effects may come from a system failure that, for example, allows a release of hazardous materials or improper disposal of waste or if a cyber-attack shut down a hydroelectric dam so that a river would be affected.
Targeted Violence
Targeted violence is unlikely to be associated with environmental impacts.
Terrorism
A terrorism event using a WMD can kill wildlife, destroy habitat, and contaminate critical resources in the food chain.
Mass Migration
Mass migration is unlikely to be associated with environmental impacts, though increased motorists on the road could lead to increases in pollution.
12.4.5 ECONOMIC IMPACTS
Cyber-Attack
Economic impacts can be far-reaching if a cyber-attack or space weather event is prolonged for a week or longer. Cyber-attacks can have extensive fiscal impacts. Companies and government services can lose large sums of unrecoverable revenue from site downtime and possible compromise of sensitive confidential data. Cyber incidents could result in the theft or modification of important data—including personal, agency, or corporate information— and the sabotage of critical processes, including the provision of basic services by government or private-sector entities.
Targeted Violence
The economic impact price tag of potential losses from targeted violence could be huge if lives are lost, jobs are lost, and assets are damaged. Violence can cause fear in residents and visitors to go into public spaces in the County, which could affect the economy.
Terrorism
The economic impact price tag of potential losses from terrorism could be huge if lives are lost, jobs are lost, and assets are damaged. Terrorism can cause fear in residents and visitors to go into public spaces in the County, which could affect the economy.
Mass Migration
Monterey County’s economy is primarily based upon tourism in the coastal regions and agriculture in the Salinas Valley. In 2019, Monterey County agriculture accounted for a production value of over $4.4 billion. The Agricultural industry generates $11.7 billion in Packet Page 409
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economic output and one in five jobs in Monterey County directly attributable to the agricultural industry. 52 Tourism spending in the County annually is approximately $3.24 billion and supports 27,000 jobs and generates $153 million in local tax revenue. 53 Therefore, if mass migration risks impact either of these industries, economic impacts could be severe.
12.5 FUTURE TRENDS IN DEVELOPMENT
Cyber-Attack
The County will continue to be impacted and compelled to respond to cyber-attacks in the future. The nature of these attacks is projected to evolve in sophistication over time. The County and its incorporated jurisdictions are expected to remain vigilant in their efforts to prevent attacks from occurring or disrupting business operations. The reality remains that many computers and networks in organizations of all sizes and industries around the US will continue to suffer intrusion attempts on a daily basis from viruses and malware that are passed through websites and emails.
Targeted Violence
Future economic, cultural, and societal trends are likely to impact the frequency and magnitude of targeted violence incidents. Additionally, studies have linked high temperatures with increases in intense violence. 54 Increasing evidence indicates that climate change is causally associated with collective violence, generally in combination with other factors. Increased temperatures and extremes of precipitation with their associated consequences, including resultant scarcity of cropland and other key environmental resources, are major pathways by which climate change leads to collective violence. 55
Terrorism
The agencies and organizations involved with terrorism in the County, specifically threat analyses and threat reduction, are examining the challenges presented by future development and expansion. Individually, and in collaboration with task forces and other facilities, plans are underway for continuation, changes and/or expansion of current initiatives. Buildings and other structures constructed to resist earthquakes and fires usually have qualities that also limit damage from blasts and resist fire spread and spread of noxious fumes in the event of a terrorist attack.
52 Economic Contributions of Monterey County Agriculture, Monterey County Agricultural Commissioner’s Office (June 2020)
53 2020-2021 Annual Report, Monterey County Convention & Visitors Bureau 54 Heat and Violence, Craig A. Anderson, Current Directions in Psychological Science (February 2001) 55 Climate Change and Collective Violence, Barry S. Levy, Victor W. Sidel, and Jonathan A. Patz, Annual Review of Public Health (March 2017)
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Mass Migration
Agricultural employment in the County has seen large increases in the past 10-years and could continue to see increases. Tourism in Monterey County is likely to expand and therefore, the risk of tourism associated with mass migration could increase.
Special event incidents occur when any large crowd of persons gather. For events having the potential for large crowds or mob activity, pre-planning and permits are issued, so potential disturbances are quelled through the presence of sufficient law enforcement personnel, preplanning for crowd and traffic control.
Climate change is likely to exacerbate hazard risk and therefore, the risk of hazard-induced migration is likely to increase in the future. This dangerous situation for vulnerable communities is a perfect example of how the climate crisis magnifies and upholds existing inequities associated with racism, extreme income inequality, and other structural disparities.
As average temperatures rise and heat waves and wildfires get more frequent and severe, farmworkers will be at an ever-heightened risk of heat- and smoke-related illnesses. California as a whole is seeing this layering of crises unfold in real time, as the state battles COVID-19, wildfires of historic proportions, and scorching heat waves.
12.6 ISSUES
Issues associated with Human-Caused Hazards in Monterey County include:
• 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.
• Continue to improve response times for public safety throughout the County so as to reduce exposure to human-caused incidents. Maintain appropriate staffing levels of public safety personnel to address vulnerabilities identified in this chapter. • Work with the private sector to enhance and create business continuity plans to be followed in the event of an emergency
• Participate in regional, state, and federal efforts to gather terrorism information at all levels and keep public safety officials briefed at all times regarding local threats. Further develop response capabilities based on emerging threats.
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13. PUBLIC HEALTH HAZARDS
13.1 OVERVIEW
The US Center for Disease Control defines a disease outbreak as the occurrence of more cases of disease than normally expected within a specific place or group of people over a given period of time. An epidemic is the spread of an infectious disease beyond a local population, reaching people in a wider geographical area. Several factors determine whether an outbreak will become an epidemic including the ease with which the disease spreads from vectors, such as animals, to people and the ease with which it spreads from person to person.
A pandemic is an epidemic that occurs worldwide or over an exceptionally large area and affects a large number of people or animals. Pandemics can greatly increase morbidity and mortality over a wide geographic area and cause significant economic, social, and political disruption. Evidence suggests that the likelihood of pandemics has increased over the past century because of increased global travel and integration, urbanization, changes in land use, and greater exploitation of the natural environment.
Pandemics are hazards that have a long duration. Though daily impacts may be low, cumulative impacts are likely to be overwhelming for both the health system and the community. During a moderate pandemic, Monterey County could see a sustained increase in intensive care unit admissions, in emergency department (ED) admissions, in patients needing to be placed in respiratory isolation, and in deaths. Capacity to provide medical care, including basic emergency medical system (EMS), hospital ED services, and isolation rooms, will be reduced. At the same time, a higher than usual absenteeism rate for all employees is expected.
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13.1.1 INFLUENZA
Epidemics of the flu typically occur in the fall and
winter. The flu can cause mild to severe illness, and
at times can lead to death. Anyone can get sick
with the flu, but some people are at a higher risk of
flu-related complications if they get sick. This
includes older and younger people and people with
certain chronic medical conditions.
Because flu seasons fluctuate in length and
severity, a single estimate cannot be used to
summarize influenza-associated deaths. The US
Centers for Disease Control and Prevention (CDC)
estimates that during the 2019–2020 flu season 38
million people fell ill, 18 million people went to a
health care provider, 400,000 were hospitalized,
and 22,000 died. Yearly vaccination is the primary
method for preventing influenza.
H1N1
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 (A/H1N1) in Mexico and the United
States. The disease spread rapidly, and in June the
WHO declared an H1N1 pandemic, marking the
first global pandemic since the 1968 Hong Kong flu.
In October, the US declared H1N1 a national
emergency. In August 2010, the WHO declared an
end to the pandemic globally. H1N1 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.
H5N1/H7N9
The highly pathogenic H5N1 avian influenza virus is
an influenza A subtype that occurs mainly in birds,
causing high mortality among birds and domestic
poultry. More than 700 human infections with
H5N1 viruses have been reported to WHO from
primarily 15 countries in Asia, Africa, the Pacific,
Historic Hazards
1918 Influenza Pandemic
The 1918 influenza pandemic was caused by
an H1N1 virus of avian origin. The pandemic
spread worldwide from 1918-1919. An
estimated 500 million people became
infected and 50 million died. An estimated
675,000 deaths occurred in the US.
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Europe, and the Near East since November 2003. Indonesia, Vietnam, and Egypt have reported the highest number of human H5N1 cases to date. The first report of a human infection with H5N1 in the Americas was in Canada in January of 2014 and occurred in a traveler recently returning from China. Although human infections with this virus are rare, approximately 60% of the cases have died.
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 H5N1 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.
13.1.2 CORONAVIRUSES
Coronaviruses are a large group of viruses that cause diseases in animals and humans. They often circulate among camels, cats, and bats, and can sometimes evolve and infect people. In animals, coronaviruses can cause diarrhea in cows and pigs, and upper respiratory disease in chickens. In humans, the viruses can cause mild respiratory infections, like the common cold, but can lead to serious illnesses, like pneumonia. Coronaviruses are named for the crown-like spikes on their surface. Human coronaviruses were first identified in the mid-1960s. They are closely monitored by public health officials.
Severe Acute Respiratory Syndrome (SARS)
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 worldwide became sick with SARS during the 2003 outbreak and 774 died. In the United States, only 11 people had laboratory evidence of SARS-CoV infection. All of these people had traveled to parts of the world where SARS was present. SARS did not spread more widely in the United States.
Since 2004, there have not been any known cases of SARS reported anywhere in the world.
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% to 20% 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-toperson 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 their mouth, nose, or Packet Page 415
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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.
Middle East Respiratory Syndrome (MERS)
Middle East Respiratory Syndrome (MERS) is an illness caused by a coronavirus called Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Most MERS patients developed severe respiratory illness with symptoms of fever, cough, and shortness of breath. About 3 or 4 out of every 10 patients reported with MERS have died.
Health officials first reported the disease in Saudi Arabia in September 2012. Through retrospective (backward-looking) investigations, they later identified that the first known cases of MERS occurred in Jordan in April 2012. So far, all cases of MERS have been linked through travel to, or residence in, countries in and near the Arabian Peninsula. The largest known outbreak of MERS outside the Arabian Peninsula occurred in the Republic of Korea in 2015. The outbreak was associated with a traveler returning from the Arabian Peninsula.
MERS-CoV has spread from ill people to others through close contact, such as caring for or living with an infected person. MERS can affect anyone, and MERS patients have ranged in age from younger than 1 to 99 years old. The CDC continues to closely monitor MERS globally and recognizes the potential for MERS-CoV to spread further and cause more cases globally and in the US.
Novel Coronavirus (COVID-19)
Coronavirus Disease 2019 (COVID-19) is a contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019 and spread worldwide, leading to an ongoing pandemic.
Symptoms of COVID-19 are variable, but often include fever, cough, headache, fatigue, breathing difficulties, and loss of smell and taste. The incubation period for COVID-19 is thought to extend to 14 days, with a median time of 4-5 days from exposure to symptoms onset.
COVID-19 transmits when people breathe in air contaminated by droplets and small airborne particles containing the virus. This risk is highest when people are in close proximity, but they can be inhaled over longer distances, particularly indoors. Transmission can also occur if splashed or sprayed with contaminated fluids in the eyes, nose, or mouth, and, rarely, via contaminated surfaces. People remain contagious for up to 20 days and can spread the virus even if they do not develop symptoms. Age and existing comorbidities are a strong risk factor for severe illness, complications, and death. A large cohort that included more than 44,000 people with COVID-19 from China, showed that illness severity can range from mild to critical:
• Mild to moderate (mild symptoms up to mild pneumonia): 81% • Severe (dyspnea, hypoxia, or more than 50% lung involvement on imaging): 14% • Critical (respiratory failure, shock, or multiorgan system dysfunction): 5% Packet Page 416
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In this study, all deaths occurred among patients with critical illness, and the overall case fatality ratio (CFR) was 2.3%. The CFR among patients with critical disease was 49%. 56 Among US COVID-19 cases reported January 22–May 30, 2020, the proportion of people who were hospitalized was 14%, including 2% admitted to the intensive care unit. Overall, 5% of patients died. 57
Several COVID-19 vaccines have been approved and distributed in various countries, which have initiated mass vaccination campaigns. Other preventive measures include physical or social distancing, quarantining, ventilation of indoor spaces, covering coughs and sneezes, hand washing, and keeping unwashed hands away from the face. The use of face masks or coverings has been recommended in public settings to minimize the risk of transmissions. While work is underway to develop drugs that inhibit the virus, the primary treatment is symptomatic.
Management involves the treatment of symptoms, supportive care, isolation, and experimental measures. COVID-19 is the most recent (and still active in 2022) pandemic declared by the World Health Organization.
13.1.3 VIRAL HEMORRHAGIC FEVERS
Viral hemorrhagic fevers (VHFs) are a group of illnesses caused by several distinct families of viruses. VHFs represent 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 (bleeding); however, the bleeding itself is rarely life-threatening. 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 host species, the virus, and the disease it causes are usually seen only where the host species live.
Ebola
The 2014 Ebola virus outbreak was unprecedented in geographical reach and impact on health care systems across the globe. This was the largest and deadliest Ebola virus outbreak ever recorded. It was the first occurrence of the virus in the West African countries of Guinea, Liberia, Sierra Leone, Nigeria, Mali, and Senegal. 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.
56 Wu Z, McGoogan JM. Characteristics of and Important Lessons from the Coronavirus Disease 2019 (COVID-19) Outbreak in China: Summary of a Report of 72314 Cases from the Chinese Center for Disease Control and Prevention. JAMA. 2020 Feb 24;323(13):1239–42. 57 Stokes EK, Zambrano LD, Anderson KN, et al. Coronavirus Disease 2019 Case Surveillance — United States, January 22–May 30, 2020. MMWR. 2020 Jun 19;69:759–765.
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In August 2014, two US healthcare workers returned 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 Ebola 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-agency emergency exercises in case the spread of Ebola became a pandemic.
Hantavirus
Hantavirus is a rodent-borne disease. It was discovered in 1993 in the southwestern US, and it has been determined that the disease had been present, but unrecognized, at least as early as 1959. It has now been identified in over half of the states of the US In 2013, seven cases of hantavirus occurred in Yosemite National Park. Hantavirus has also been detected in the Sierra Nevada region.
The hantavirus spreads when individuals touch or eat something contaminated with infected rodent urine, droppings, or saliva. It can also be transmitted through aerosolization, which occurs when dried materials contaminated by infected rodent droppings or saliva are disturbed and brought up into the air and inhaled.
Infected persons first develop symptoms one to five weeks after exposure. Early symptoms include fever, headache, and muscle aches, especially in the thighs, hips, back, and shoulders.
Other early symptoms include dizziness, chills, nausea, vomiting, diarrhea, and abdominal pain.
After two to seven days of these symptoms, patients develop breathing difficulties that range from cough and shortness of breath to severe respiratory failure. Approximately 40% of hantavirus patients die from the disease.
13.1.4 TICK & MOSQUITO BORNE ILLNESS
Ticks are small, insect-like creatures most often found in naturally vegetated areas. They feed by attaching to animals and humans, sticking their mouthparts into the skin, and sucking blood for up to several days. Ticks do not fall from trees, jump, or fly. Most species are found on wild grasses and low plants. Adult ticks wait at the ends of grass or other foliage for a host to brush by so they may attach. Sometimes ticks carry bacteria or viruses that can be transmitted to a person while the tick is attached and feeding. The following species of ticks are known to commonly bite humans:
• Western blacklegged tick (Ixodes pacificus) • Brown dog tick (Rhipicephalus sanguineus) • American dog tick (Dermacentor variabilis) • Ornithodoros hermsi • Pacific Coast tick (Dermacentor occidentalis) • Ornithodoros parkeri • Wood tick (Dermacentor andersoni) • Ornithodoros coriaceus Packet Page 418
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Tularemia
Tularemia, named after Tulare County in California, where it was first described in 1911, is a tick-borne disease of animals and humans caused by the bacterium Francisella tularensis.
Tularemia is similar to plague but is typically spread differently. Humans usually become infected with Tularemia by tick and deer fly bites, skin contact with infected animals, ingestion of contaminated water or meat, or inhalation of contaminated dusts or aerosols. Symptoms vary depending upon the route of infection.
Rabbits, hares, and rodents are especially susceptible and often die in large numbers during outbreaks. Although Tularemia can be life-threatening, most infections can be treated successfully with antibiotics. Steps to prevent Tularemia include use of insect repellent, wearing gloves when handling sick or dead animals, and not mowing over dead animals. In the United States, naturally occurring infections have been reported from all states except Hawaii.
Lyme Disease
Lyme disease, named after the city in Connecticut, where it was first identified in 1975, is a tickborne disease caused by the bacterium Borrelia burgdorferi, which normally lives in mice, squirrels, and other small animals. It is transmitted among these animals and to humans through the bites of certain species of ticks. In the northeastern and north-central United States, the black-legged tick (or deer tick, Ixodes scapularis) transmits Lyme disease. In the Pacific coastal United States, the disease is spread by the western black-legged tick (Ixodes pacificus). Other major tick species found in the United States have not been shown to transmit the disease.
Typical symptoms include fever, headache, fatigue, and a skin rash. If left untreated, infection can spread to joints, the heart, and the nervous system. Lyme disease is diagnosed based on symptoms, physical findings (e.g., rash), and the possibility of exposure to infected ticks.
Laboratory testing is helpful in later stages of the disease. Most cases of Lyme disease can be treated successfully with a few weeks of antibiotics. Steps to prevent Lyme disease include using insect repellent, removing ticks promptly, landscaping, and integrated pest management.
The ticks that transmit Lyme disease can occasionally transmit other tick-borne diseases as well.
Rocky Mountain Spotted Fever
Rocky Mountain spotted fever is a potentially fatal tick-borne disease caused by the bacterium Rickettsia rickettsii. It is transmitted to humans by the bite of an infected American dog tick (Dermacentor variabilis), Rocky Mountain wood tick (Dermacentor andersoni), or brown dog tick (Rhipicephalus sanguineus).
Typical symptoms include fever, headache, abdominal pain, vomiting, and muscle pain. A rash may also develop, but is often absent in the first few days, and in some patients, never develops. Rocky Mountain spotted fever can be a severe or even fatal illness if not treated in the first few days of symptoms. It can be treated successfully with a few weeks of antibiotics.
Steps to prevent the disease include using insect repellent, removing ticks promptly, Packet Page 419
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landscaping, and integrated pest management. The ticks that transmit Rocky Mountain spotted fever can occasionally transmit other tick-borne diseases as well.
Malaria
Malaria is a sometimes-fatal mosquito-borne disease caused by a parasite that commonly infects the Anopheles mosquito, which feeds on humans. People who contract malaria are typically extremely sick with high fevers, chills, and flu-like illness. Although malaria can be fatal, illness and death can usually be prevented.
On average 1,500 cases of malaria are diagnosed in the United States each year. The vast majority are in travelers and immigrants returning from countries where malaria transmission occurs, many from sub-Saharan Africa and South Asia. In many temperate areas, such as western Europe and the United States, economic development and public health measures have succeeded in eliminating malaria. However, most of these areas have Anopheles mosquitoes that can transmit malaria, and reintroduction of the disease is a constant risk.
West Nile Virus
West Nile Virus is a potentially serious mosquito-borne that may affect residents in the County.
Experts believe West Nile Virus is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall. Mosquitoes transmit the virus to birds, livestock, and humans. Between 1999 and 2019, a total of 51,801 cases of West Nile Virus disease in people was reported to CDC, 7,026 of which were in California.
According to the CDC, approximately 80% of people who are infected with West Nile Virus will show no symptoms. Up to 20% have symptoms such as fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms can last for as short as a few days, though even healthy people have become sick for several weeks. About 1% of people infected with West Nile Virus will develop severe illness, with symptoms that can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis. These symptoms may last several weeks, and neurological effects may become permanent. There is no specific treatment for West Nile Virus infection. In more severe cases, people may need to go to the hospital where they can receive supportive treatment including intravenous fluids, help with breathing and nursing care.
Dengue Fever
Dengue is a mosquito-borne disease caused by any of four closely related dengue viruses (DENV-1, DENV-2, DENV-3, and DENV-4). People get dengue from the bite of an infected mosquito. The mosquito becomes infected when it bites a person who has dengue virus in their blood. It takes a week or more for the dengue virus to replicate in the mosquito; then the mosquito can transmit the virus to another person when it bites. Dengue is transmitted by the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus). Dengue virus cannot be transmitted from person to person.
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Generally, younger children and those with their first dengue infection have a milder illness than older children and adults. The main symptoms are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, bruising, and sometimes mild bleeding from the nose or mouth. Severe dengue patients proceed to experience more bleeding, severe pain in the abdomen, respiratory distress, and fluid accumulation in the abdomen and around the lungs as the smallest blood vessels (capillaries) begin to leak. If not treated, severe dengue can result in death. There is no specific treatment for dengue infection.
Rest and fluids are generally sufficient for persons with dengue. Severe dengue may require hospitalization and intensive medical care.
Zika Virus
Zika is a mosquito-borne disease. 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 by an infected mosquito. People usually do not get sick enough to go to the hospital, and they rarely die of Zika. 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, 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 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. 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 microcephaly (abnormally small head and brain) in newborns, as well as Zika and Guillain-Barré Syndrome, a disease affecting the nervous system. Studies are ongoing to further evaluate these associations.
13.1.5 VALLEY FEVER
Valley Fever, also called coccidioidomycosis, is an infection caused by the fungus Coccidioides.
The illness is caused by breathing in a fungus which lives naturally in the soil of nearby San Luis Obispo and Santa Barbara Counties. People get sick by breathing in a form of the Valley Fever fungus called spores. Spores are too small to be seen. They can get into the air with dust when it is windy or when dirt is disturbed. In extremely rare cases, the fungal spores can enter the skin through a cut, wound, or splinter and cause a skin infection. Valley Fever cannot be spread from one person to another or from an animal to a person.
Most people who become infected with Valley Fever (60%) do not experience any symptoms and do not need treatment. Around 30 to 40% of people develop flu-like symptoms such as severe fatigue, cough, fever, heavy sweating at night, loss of appetite, muscle, and joint aches, and sometimes a rash. Approximately 5 to 10% of people who get Valley Fever will develop serious or long-term problems in their lungs. In an even smaller percentage of people (about 1%), the infection spreads from the lungs to other parts of the body, such as the central Packet Page 421
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nervous system (brain and spinal cord), skin, or bones and joints. This type of infection can be serious and is sometimes fatal.
Symptoms of valley fever may appear between 1 and 3 weeks after a person breathes in the fungal spores and usually last for a few weeks to a few months. Valley Fever is more common among older adults, though anyone of any age can contract it. Several groups of people are at higher risk for developing the severe forms of Valley Fever, including African Americans, Filipinos, women in the third trimester of pregnancy, and people with weak immune systems.
Valley Fever appears to be on the rise in recent years, with 2017 bringing the highest number of recorded cases on record to California. According to the CDC, while the reasons for the increased incidence in Valley Fever in 2016 are not known, climatic and environmental factors favorable to Valley Fever proliferation and airborne release might have contributed, including rainfall after several years of drought and soil disturbance resulting from construction. The UC Davis Valley Fever Center attributes the increase in cases to drought conditions and firefighting equipment stirring up fungus in the soil. A March 2013 Morbidity and Mortality Weekly Report published by the Centers for Disease Control and Prevention (CDC) and referenced in the 2018 California State Hazard Mitigation Plan notes that more than 20,000 cases of Valley Fever are reported each year in the United States, but many more cases likely go undiagnosed. Some researchers estimate that each year the fungus infects more than 150,000 people, many of whom are sick without knowing the cause or have symptoms so mild they are not recognized.
13.1.6 POLICIES, PLANS, AND REGULATORY ENVIRONMENT
United States Department of Health and Human Services
The US Department of Health and Human Services has statutory responsibility for preventing the introduction, transmission, and spread of communicable diseases in the United States. The Center for Disease Control and Prevention (CDC) is housed within the Department of Health and Human Services and is responsible for controlling the introduction and spread of infectious diseases. The CDC’s roles include:
• Instituting public education and awareness related to disease spread and prevention • Studying and tracking transmission rates, treatment options, and vaccines • Maintaining active surveillance of diseases through investigation and data collection, analysis, and distribution
• Developing and implementing operational programs and guidance relating to environmental health problems
• Conducting research aimed at developing and testing effective disease prevention, control, and health
• Implementing a program to sustain a strong national workforce in disease prevention and control, and conducts a national program for improving the performance of clinical laboratories
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The Division of Global Migration and Quarantine works to control disease transmission internationally through the operation of Quarantine Stations at ports of entry, establishment of standards for medical examination of persons destined for the United States, and administration of interstate and foreign quarantine regulations, which govern the international and interstate movement of persons, animals, and cargo.
California Department of Public Health
The California Department of Public Health (CDPH) is responsible for protecting public health within the state of California. The CDPH consists of public health professions, researchers, scientists, doctors, nurses, and other staff members who aid in implementing the organizations programs and services. The essential functions of the CDPH are comprehensive in scope and include infectious disease control and prevention, food safety, environmental health, laboratory services, patient safety, emergency preparedness, chronic disease prevention and health promotion, family health, health equity and vital records and statistics.
Monterey County Health Department
The Monterey County Health Department exists to enhance, protect, and improve the health of the people in Monterey County. To accomplish this, the Department provides a wide variety of health-related services in the areas of public health, environmental health, behavioral health, and clinic services. The Public Health Bureau has programs that cover several essential public health services, including surveillance, disaster preparedness, diagnosing and addressing health problems, outreach, and education, and mobilizing community partnerships to identify and solve health problems. The Communicable Disease Prevention and Control Unit is responsible for preventing and controlling the spread of infectious diseases.
13.2 HAZARD PROFILE
The severity of human health hazards is dependent upon the hazard and the population exposed to it. As the population increases, so does the risk of exposure to public health hazards. The key to reducing the disease hazard is isolation so that the infected population does not continue to spread the hazard to the uninfected population. For disease health hazards, promoting education and personal preparedness will help to mitigate and reduce the severity of the hazard.
13.2.1 HISTORY
Table 13-1 lists communicable disease cases in Monterey County from 2009 to 2019 for select disease discussed in this plan.
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Table 13-1: Selected Communicable Disease Cases in Monterey County (2009-2019) Table 13-1
Selected Communicable Disease Cases in Monterey Country (2009-2019) Disease Year
2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Total Dengue Fever 0 1 1 1 0 1 2 1 3 0 1 12
Hantavirus 0 0 0 0 0 0 0 0 0 0 0 0
Lyme Disease 0 1 1 1 1 0 2 2 0 0 3 12
Malaria 2 3 3 0 1 1 0 0 0 1 2 13
Rickettsiosis 0 0 1 2 1 1 0 0 0 0 1 6
Tularemia 0 0 0 0 0 0 0 0 1 0 1 2
Valley Fever 39 56 67 76 69 24 38 79 191 238 164 1,041
West Nile Virus 1 0 0 1 0 0 0 1 0 1 0 4
Zika Virus 0 0 0 0 0 0 0 5 1 0 0 6
Source: California Department of Public Health- West Nile Virus Cases, 2006-present and Infectious Diseases by Disease, County, Year, and Sex There were two confirmed cases of SARS in California during the worldwide outbreak in 2002- 2003, neither of them in Monterey County. From 2011 through 2015, there were 16 cases of hantavirus in California, neither occurred in Monterey County.
An estimated 22,500 to 90,000 Monterey County residents become ill from influenza each flu season. Table 13-2 lists severe influenza cases by flu season for residents under 64 in Monterey County from 2013-2018.
Table 13-2: Severe Influenza Cases (Age 64 and Younger) By Flu Season Table 13-2
Severe Influenza Cases in Monterey County (Age 64 and Younger) by Flu Season: 2013-2018 Flu Season ICU Admissions Fatalities
2013-2014 Flu Season 12 7
2014-2015 Flu Season 6 2
2015-2016 Flu Season 2 1
2016-2017 Flu Season 8 4
2017-2018 Flu Season* 6 7
*Data should be considered provisional
Source: Monterey County Health Department Epidemiology & Surveillance Unit, Influenza - Local Data, Current as of March 10, 2018
Pandemics
There have been six pandemics since 1900. The previous pandemics occurred in 1918-1920, 1957-1958, 1968- 1969, 1977-1978, 2009-2010, and 2019-present. 1918 Pandemic: The 1918-1920 Pandemic, commonly referred to as the Spanish Flu, was unusually severe, infecting close to one-third of the world’s population, or 500 million people.
The 1918 pandemic had an extensive mortality rate, killing as much as 1% of the world’s population, or 40 million people worldwide, including about 675,000 in the United States.
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1957-1958 (H2N2 Virus) Pandemic: In February 1957, a new influenza A (H2N2) virus emerged in East Asia, triggering a pandemic (“Asian Flu”). This H2N2 virus was comprised of three different genes from an H2N2 virus that originated from an avian influenza A virus, including the H2 hemagglutinin and the N2 neuraminidase genes. It was first reported in Singapore in February 1957, Hong Kong in April 1957, and in coastal cities in the United States in summer 1957. The estimated number of deaths was 1.1 million worldwide and 116,000 in the United States.
1968 (H3N2 Virus) Pandemic: The 1968 pandemic was caused by an influenza A (H3N2) virus comprised of two genes from an avian influenza A virus, including a new H3 hemagglutinin, but also contained the N2 neuraminidase from the 1957 H2N2 virus. It was first noted in the United States in September 1968. The estimated number of deaths was 1 million worldwide and about 100,000 in the United States. Most excess deaths were in people 65 years and older. The H3N2 virus continues to circulate worldwide as a seasonal influenza A virus. Seasonal H3N2 viruses, which are associated with severe illness in older people. 2009 (H1N1 Virus) Pandemic: In the spring of 2009, a novel influenza A (H1N1) virus, commonly known as swine flu emerged. It was detected first in the United States and spread quickly across the US and the world. This new H1N1 virus contained a unique combination of influenza genes not previously identified in animals or people. The H1N1 virus was quite different from H1N1 viruses that were circulating at the time of the pandemic. Few young people had any existing immunity (as detected by antibody response) to the H1N1 virus, but nearly one-third of people over 60 years old had antibodies against this virus, likely from exposure to an older H1N1 virus earlier in their lives. Since the H1N1 virus was different from circulating viruses, vaccination with seasonal flu vaccines offered little cross-protection against H1N1 virus infection
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 (A/H1N1) in Mexico and the United States. The disease spread rapidly, and in June the WHO declared an H1N1 pandemic. In October, the US declared H1N1 a national emergency.
From April 12, 2009, to April 10, 2010, the CDC estimated there were 60.8 million cases (range:
43.3-89.3 million), 274,304 hospitalizations (range: 195,086-402,719), and 12,469 deaths (range: 8868-18,306) in the United States due to the H1N1 virus. Additionally, the CDC estimated that 151,700-575,400 people worldwide died from H1N1. Globally, 80% of virusrelated deaths were estimated to have occurred in people younger than 65 years of age, which differs greatly from typical seasonal influenza epidemics, during which about 70% to 90% of deaths are estimated to occur in people 65 years and older. 58 58 2009 H1N1 Pandemic (H1N1pdm09 virus), Centers for Disease Control and Prevention (CDC) Packet Page 425
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In Monterey County, the 2009 pandemic led to 16 ICU admissions and 3 fatalities. 59 In August 2010, the WHO declared an end to the pandemic globally. H1N1 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.
COVID-19 (SARS-CoV-2) Pandemic: Currently, COVID-19, a contagious disease caused by a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an ongoing pandemic, which has had a large effect worldwide and on Monterey County.
COVID-19 was declared a Public Health Emergency of International Concern in January 2020 by the World Health Organization. On February 4, 2020, the US declared a public health emergency. On February 28, 2020, the first case of community spread was detected in California and by March 4, the first COVID-19 death in California occurred. Therefore, on March 4, 2020, Governor Newsom declared a State of Emergency and on March 6th, the Monterey County Board of Supervisors also proclaimed a state of emergency. On March 13th, the President of the US declared a National Emergency. Local emergencies were also proclaimed by all incorporated jurisdictions in Monterey County by the end of March 2020.
On March 13, 2020, 12 passengers from the Diamond Princess Cruise Ship were quarantined in Asilomar Hotel, Pacific Grove while undergoing testing. On March 17, the first two cases of COVID-19 in Monterey County were confirmed and the County of Monterey Health Officer issued a Shelter-in-Place Order. The first death due to complications from COVID-19 in Monterey County occurred on March 21.
As of October 9, 2021, according to data from the Centers for Disease Control and Prevention, the United States has had a total of 44,217,318 total cases of COVID-19 and 711,020 deaths caused by COVID-19. 60 As of October 11, 2021, the State of California has had 4,553,194 confirmed cases of COVID-19, resulting in 69,741 deaths. The current daily average of new cases is 5,212 with 92 daily average deaths per day. Statewide, 71.4% of people have been fully vaccinated, and 9.9% of people have been partially vaccinated against COVID-19. 61 As of October 11, 2021, there have been 48,416 confirmed cases of COVID-19 and 584 COVID19 deaths in Monterey County. Figure 13-1 shows cases of COVID-19 among Monterey County residents by date of report.
59 Influenza - Local Data, Monterey County Health Department 60 United States COVID-19 Cases, Deaths, and Laboratory Testing (NAATs) by State, Territory, and Jurisdiction, Centers for Disease Control and Prevention (CDC), Accessed October 12, 2021 61 Tracking COVID-19 in California, State of California, Accessed October 12, 2021 Packet Page 426
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Figure 13-1
COVID-19 Cases Among Monterey County Residents by Date
Figure 13-1: COVID-19 Cases Among Monterey County Residents by Date As seen in the Figure 13-1, Monterey County saw cases start to grow in the summer of 2020, with its first large spike in COVID-19 cases in August of 2020. The largest spike in cases occurred in December and January 2021, and began to decline in the Spring of 2021, with some growth in cases occurring again in July and August of 2021.
Table 13-3 lists COVID-19 cases by age group in Monterey County and Figure 13-2 shows COVID-19 cases by region of residence, as of October 11, 2021. 62 Table 13-3: COVID-19 Cases Among County Residents by Age Group Table 13-3
COVID-19 Cases Among Monterey County Residents by Age Group Age in Years Incident Cases Percent of Total Cases
0-17 6,851 14.15%
18-24 6,469 13.36%
25-34 9,800 20.23%
35-44 9,044 18.67%
45-54 7,361 15.20%
55-64 5,123 10.58%
65-74 2,300 4.75%
75-110 1,471 3.04%
Other 12 0.02%
62 2019 Novel Coronavirus (2019-NCoV) - Local Data, Monterey County Packet Page 427
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Figure 13-2
COVID-19 Cases Among Monterey County Residents by Region of Residence Figure 13-2: COVID-19 Cases Among Monterey County Residents by Region of Residence Table 13-4 lists severe cases of COVID-19 by age group based on the number of hospitalized individuals in Monterey County.
Table 13-4: Severe COVID-19 Cases Among Residents by Age Group Table 13-4
Severe COVID-19 Cases Among Monterey County Residents by Age Group Age in Years Hospitalized Individuals Proportion of Hospitalized Cases 0-17 49 2.71%
18-24 47 2.60%
25-34 180 9.94%
35-44 227 12.54%
45-54 322 17.79%
55-64 344 19.01%
65-74 309 17.07%
75-110 332 18.34%
Total 1810 100.00%
Table 13-5 lists COVID-19 fatalities by age group in Monterey County.
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Table 13-5: COVID-19 Fatalities Among Residents by Age Group Table 13-5
COVID-19 Fatalities Among Monterey County Residents by Age Group Age in Years Number of Fatalities Proportion of Fatalities 0-34 13 2.22%
35-44 15 2.56%
45-54 49 8.36%
55-64 104 17.75%
65-74 126 21.50%
75+ 279 47.61%
Total 586 100.00%
13.2.2 LOCATION
All of the County is susceptible to the human health hazards discussed in this chapter. While some hazards, such as the West Nile Virus and Lyme Disease, can have a geographic presence within the County, other diseases can cause exposure to the County from outside the local region. Local residents who travel can become exposed to diseases while abroad and bring the diseases back with them, potentially placing the region at risk for exposure. COVID-19, for example, may be transported into the County, through residents and visitors who travel extensively. It is difficult to map the extent of human-health hazards compared to others, such as floods, wildfires, and dam failures.
13.2.3 FREQUENCY
Due to increased air travel and growing population, the probability of a communicable disease epidemic is a growing threat. Certain human health hazards, such as influenza, can be expected seasonally, with variations on specific strains year to year. Additionally, tick-borne diseases are likely to increase during spring and fall, when people participate in outdoor activities such as hiking.
The frequency of other health hazards is difficult to establish and depends largely on the unique circumstances surrounding a localized outbreak and its subsequent expansion into epidemics.
While the probability of a major infectious disease outbreak is relatively low, it can have catastrophic social and economic consequences.
Influenza: According to the CDC, influenza has a predictable pattern and a near certainty of occurrence. The CDC estimated that on average, about 8% of the US population gets sick from flu each season, with a range of between 3% and 11%, depending on the season. 63 COVID-19: A report released by the World Health Organization and the China Joint Commission found that transmission rates of COVID-19 vary based on location. In general, between 1% and 63 Seasonal Incidence of Symptomatic Influenza in the United States, Centers for Disease Control and Prevention Packet Page 429
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5% of people in contact with a confirmed case of the virus subsequently, become a laboratoryconfirmed case of COVID-19. 64 West Nile Virus: In California, mosquitoes are monitored and controlled primarily to reduce cases of West Nile Virus, malaria, encephalitis, dog heartworm, and sensitivity to bites. Human mosquito-borne diseases, including West Nile Virus, have declined significantly in California since the creation of mosquito and vector control agencies.
Lyme Disease: There have been 12 confirmed cases of Lyme disease in Monterey County between 2009-2019. Cases are expected to continue to develop, and instances may increase with warming temperatures due to climate change.
The frequency and probability of other diseases discussed in this profile are unpredictable and contingent on factors such as public awareness, treatment options, and vaccination rates.
13.2.4 SEVERITY
The severity of the human health hazard varies from individual to individual. Typically, young children and older adults are more susceptible to acquiring communicable diseases due to developing or diminishing immune systems or experiencing adverse effects from extreme weather conditions. These populations often experience the most severe of symptoms, as their immune systems are not capable of fighting off infection or efficiently regulating temperature.
In general, severity varies depending on the pathology of the disease, the health of the infected, and the availability of treatments for alleviating symptoms or curing the disease.
13.2.5 WARNING TIME
Warning time for public health risks varies from a few hours or days to a few months, depending on the illness and outbreak to the population.
13.3 SECONDARY HAZARDS
Human health hazards are not like natural hazards that have measurable secondary impacts, such as earthquakes, floods, or wildfires. This is primarily due to the fact that human health hazards do not generally impact buildings and critical infrastructure as natural hazards do. The largest secondary impact caused by human health hazards would be economic. Large outbreaks of any human health hazard could reduce the workforce significantly, causing businesses and agencies to close or be greatly impacted.
Moreover, as the COVID-19 pandemic is revealed, a pandemic can add significant challenges to ongoing hazard mitigation efforts, not to mention confusing and complicating response efforts for other natural hazard events. This is an emerging issue, and developments result in guidance 64 Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) Packet Page 430
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changes. Mitigating the impacts of the pandemic, in many instances, means mitigating the impact of a pandemic to other hazards that could occur simultaneously.
Another secondary impact could be stigmatization. The fear of the health hazard and fear of the unknown could lead to isolation, violence, and self-inflicted injury. Hospitals and healthcare providers could be overwhelmed with the “worried well” seeking care and comfort. Education and providing key and critical information can reduce and mitigate this secondary risk.
13.4 RISK ASSESSMENT
13.4.1 POPULATION
All citizens in the County could be susceptible to the human health hazards discussed in this chapter. A large outbreak or epidemic, a pandemic, or a use of biological agents as a weapon of mass destruction could have devastating effects on the population. While all of the population is at risk to the human health hazards discussed in this chapter, the young and the elderly, those with compromised immune systems, and those with special needs are most vulnerable.
The introduction of a disease such as the plague or influenza could rapidly impact those at risk.
13.4.2 PROPERTY
None of the health hazards discussed in this chapter would have significant impact on the structural environment or property.
13.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
None of the health hazards discussed in this chapter would have significant impact on the critical facilities or infrastructure of the County. However, health care facilities (including longterm care and clinics and even veterinary offices) are prepared for pandemic disease hazards.
Emergency management planning incorporates all disciplines responding to an event, (fire agencies, law enforcement, first responder ground and air ambulance agencies, public health, mental and spiritual health). Planning includes identifying shelters, alternate treatment facilities, isolation capacity, and methods to immediately expand physical and human resources.
13.4.4 ENVIRONMENT
None of the health hazards discussed in this chapter would have significant impact on the environment of the planning area. While many of the vectors of the health hazards discussed in this chapter (mosquitoes, rodents, fleas, ticks, and deer flies) rely on local or regional environments for their survival, the human health hazard that they carry or potentially transmit would have no significant impact on the environment.
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13.4.5 ECONOMY
The economic impact of a human health hazard could be localized to a single region or population or could be widespread. The impact could be significant, depending on the hazard, number of cases and the availability of resources to care for those affected by the hazard.
Other financial impacts could be absorbed or managed by the organization affected.
13.5 FUTURE TRENDS IN DEVELOPMENT
Unless a catastrophic incident occurs, it is estimated that the County’s population will continue to grow. When more people visit Monterey County or move into the area, the impacts from and the potential for a pandemic outbreak rises. Urban areas, in particular, will become more vulnerable as density increases and illnesses or contamination spread more rapidly. The potential for communicable diseases and vector-borne diseases in the County is not likely to lessen or prohibit growth or development.
13.6 ISSUES
Important issues associated with the human health hazards include the following:
• Prevention through vaccination and personal emergency and disaster preparation will help to reduce the impacts of human health hazards
• Medical and response personnel need to be integrated in a unified command to provide care when needed in response to human health hazards.
• Medical and response personnel must be adequately trained and supplied. • A system needs to be in place for informing the public with a unified message about a human health hazard.
• Health agencies and facilities require surge capacity management and adaptation to the rising number and needs of the region.
• Critical facilities may not have adequate fresh air/ ventilation to be appropriate for essential work during pandemic.
• Need for additional sheltering locations in event of pandemic social distancing needs paired with another hazard event (flood, wildfire, earthquake) • COVID-19 exists as a threat to the entire population of Monterey County.
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14. SEVERE WEATHER
14.1 OVERVIEW
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: general severe weather (systems that form over wide geographic areas) and localized severe weather (systems with a more limited geographic area). The most common severe weather events that impact Monterey County and that are profiled in this chapter are:
• Severe Winter Storms
• Extreme Cold and Freeze
• Windstorms
• Extreme Heat
Due to the size of the County and changes in elevation and climate, weather conditions can vary greatly. The proximity to the Pacific Ocean both moderates and exaggerates certain types of adverse weather. Winter storms impacting coastal portions of the County tend to be more extreme than in the inland portions. The ocean’s influence is also a significant factor in moderating extreme hot and cold temperatures, hailstorms, and other cold weather events.
These events are rare and short lived, causing little if any life-threatening situations and only occasional significant damage to property or agricultural concerns.
When reading this chapter, it is important to note that when the term “severe weather” is used, it is referring in aggregate to the sub-hazards profiled in this chapter. These hazards have been grouped because each hazard can impact and has impacted the entire County and has no Packet Page 433
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clearly defined extent or location mapping. Since there is no clearly defined extent or location mapping available for these hazards, no geospatial analysis is available to support exposure or vulnerability analysis. Quantitative analysis is included from the FEMA National Risk Assessment, but the analyses for these hazards are mainly qualitative.
14.1.1 SEVERE WINTER STORMS
Most severe winter storms in Monterey County consist of heavy rain events, sometimes accompanied by thunderstorms, high winds, dense fog, hail, and freeze events. 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.
Monterey County’s weather is influenced by the Pacific Ocean and routine climate patterns such as El Niño. El Niño is the warm phase of the El Niño-Southern Oscillation cycle, a pattern found in the tropical Pacific when there are fluctuations in temperatures between the ocean and atmosphere. During El Niño, the surface winds across the entire tropical Pacific are weaker than normal and the ocean surface is at above-average temperatures in the central and eastern tropical Pacific Ocean. El Niño typically develops over North America during the winter season causing the severe winter storms experienced by the County. This climate pattern occurs every few years and brings with it above-average rain and snow across the southern region of United States, especially in California.
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 regions 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, causing flooding and mudslides.
For more information on flooding events or landslides caused by heavy rain, refer to Flooding in Section 10 or Slope Failure in Section 15.
Hail is formed when water droplets freeze and thaw as they are thrown high into the upper atmosphere by the violent internal forces of thunderstorms. Hail is sometimes associated with severe storms within Monterey County. Hailstones are usually less than two inches in diameter and can fall at speeds of 120 miles per hour (mph). Severe hailstorms can be quite destructive, causing damage to roofs, buildings, automobiles, vegetation, and crops. Dense fog is also sometimes associated with severe storms in the County. Dense fog reduces visibility making driving more dangerous. The National Weather Service issues dense fog advisories when appropriate.
14.1.2 EXTREME COLD AND FREEZE
Extreme cold often accompanies a winter storm or is left in its wake. A freeze refers to a particularly cold spell of weather where the temperature drops below 32 degrees, most Packet Page 434
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typically in the early morning hours. Usually, these cold spells will last only two or three days when the ocean influence will overcome the cold front and the early morning temperatures will return to the normal 45 to 55-degree range. Rainfall during these periods may result in snowfall in the higher elevations of the County. Prolonged exposure to cold can be life-threatening, particularly to infants and the elderly. Freezing temperatures can cause significant damage to the agricultural industry.
14.1.3 WINDSTORM
Windstorms are generally short-duration events involving straight-line winds or gusts of over 50 mph, strong enough to cause property damage. Windstorms are especially dangerous in areas with significant trees and areas with exposed property, poorly constructed buildings, 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 debris in its wake.
Damaging winds are classified as those exceeding 60 mph and can reach up to 100 mph, producing 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 primarily to differentiate from tornado winds. Most thunderstorms produce some straight-line winds as a result of outflow generated by the downdraft. • 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 5-10 minutes, with maximum wind speeds up to 168 mph. There are both wet and dry microbursts. A wet microburst is accompanied by heavy precipitation. Dry microbursts, common in 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 Packet Page 435
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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.
High winds can occur during a severe
thunderstorm, with a strong weather
system, or can flow down a mountain.
When winds are sustained at 40-50
mph, isolated wind damage is
possible. Widespread significant wind
damage can occur with higher wind
speeds. During strong thunderstorms,
straight line wind speeds can exceed
100 mph. High winds can blow objects
around and pose a significant threat to
public safety.
Windstorms can also be created by
thermally forced circulations during
the spring to summer months. Known
as sea breezes, these winds are
strongest when the land becomes
warmer than the adjacent ocean.
Driven by the differential heating of
land versus water, sea breeze
formation is conducive under synoptic
conditions that allow strong heating of
land areas. The wind direction
associated with the sea breeze is
directed inland along the surface
pressure gradient. Therefore, sea
breeze fronts generally push inland for
approximately 25 miles as the day
progresses. The sea breeze circulation
will intensify as the daytime solar
heating reaches its maximum before
diminishing and reversing to a land
breeze circulation as the land cools.
Mitigation Success Story
City of Salinas Free Tree Program
In February 2017, 60-mile per hour winds and heavy
rainfall brought down power lines and trees. Over
600 trees were lost in the storm, exacerbating a
long growing problem. The City had already lost
close to 350 trees, largely due to drought. The City
completed an Urban Forest Assessment and started
the "Free Tree--Adopt A Tree Program.” Residents
can apply to "Adopt-A-Tree" and the City will
purchase and plant a tree if the resident agrees to
water it until its established.
Planting trees is a great example of a multi-benefit
mitigation project. Trees contribute significantly to
environmental quality and human health and wellbeing. The urban forest is a form of “green infrastructure” that provides millions of dollars of
benefit at a very low cost. Trees reduce the impact
of weather and climate hazards. During storms,
trees absorb rainwater, reducing runoff and
preventing pollutants from entering waterways.
Large tree canopies create shade and conserve
energy, which reduces the impact of extreme heat
and helps meet climate change goals.
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All of Monterey County is subject to strong southeasterly winds associated with powerful cold fronts. These winds, which are usually part of a strong Pacific storm, generally occur during the winter months, from November to February. As the wind passes through the narrowing Salinas valley, the wind velocity increases and moisture-holding capacity decreases. As such, this wind is relatively hot and dry in southern portions of the valley, such as Soledad. Sea breeze winds, with average winds speeds of 10–15 mph, can be expected annually from March through October.
14.1.4 EXTREME HEAT
Extreme heat is unexpected, unusual, or unseasonable hot temperature that can create dangerous situations. Heat waves are periods of abnormally hot weather lasting days to weeks.
According to information provided by FEMA, extreme heat is defined as temperatures that hover 10 degrees or more above the average high temperature for the region and last for several weeks. Heat kills by taxing the human body beyond its abilities. In a normal year, about 175 Americans succumb to the demands of summer heat.
Ambient air temperature and relative humidity are components of heat conditions, together defining a heat index, as shown Figure 14-1. The Heat Index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature.
Figure 14-1
National Weather Service Heat Index
Figure 14-1: National Weather Service Heat Index
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14.2 HAZARD PROFILE
14.2.1 HISTORY
Severe Winter Storms and Extreme Freeze
Table 14-1 summaries severe winter storm and freeze events that have occurred in the County.
Table 14-1: Severe Winter Storms and Extreme Freeze Events (2010-2020) Table 14-1
Severe Winter Storms and Extreme Freeze Events in Monterey County (2010-2020) Date Description
11/10/2020
A cold airmass brought below freezing temperatures. Overnight low temperature records were broken in King City. Warnings were issued for the Salinas Valley where lows dropped into the 20s.
3/17/2020
A storm brought several days of showers. Vehicles were reported as spinning out on US-101 S near King City due to accumulating hail on roadway.
2/3/2020-
2/5/2020
As a low-pressure system exited, skies began to clear, and wind sheltered locations saw a drop in overnight temperatures to below freezing.
Recorded temperatures reached as low as 18 degrees.
11/29/2019 An atmospheric river caused a closure of Hwy 1 at Paul's Slide. Parkfield recorded heavy rainfall.
10/31/2019
A dry airmass and lighter winds led to freezing temperatures in the interior valleys. A Freeze Warning was issued for the Salinas Valley and Interior Monterey County.
2/17/2019 Isolated thunderstorms developed late afternoon and produced hail and lightning over the region.
2/10/2019 A cold front moved through the region. Hail covered the greens at Pebble Beach suspending final rounds of the Pro Am.
2/5/2019-
2/6/2019
A very cold airmass brought snow to lower elevation peaks prompting a rare Winter Weather Advisory. Junipero Serra Peak received about 1 ft of snow and Cone Peak received about 8 in of snow.
1/1/2019-
1/2/2019
Cold overnight temperatures in the mid-30s to low 40s across Santa Clara County resulted in two fatalities. Widespread freezing temperatures were reported elsewhere across the region.
12/28/2018-
12/29/2018
A cold dry air mass caused temperatures to drop below freezing overnight. This prompted the issuance of a freeze warning. 11/29/2018 A cool unstable air mass caused scattered thunderstorms that produced lightning and small hail.
4/16/2018 A late season storm brought rain, winds, hail, thunder, and lightning to the region.
3/3/2018 A strong cold front brought widespread rainfall causing localized flooding, strong winds, and lighting.
1/22/2017 A storm brought rain, lightning, wind, hail, snow, and record-breaking surf.
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Table 14-1
Severe Winter Storms and Extreme Freeze Events in Monterey County (2010-2020) Date Description
1/20/2017 A storm brought heavy rain, strong winds, and hail. 4/27/2016 Low level urban flooding due to heavy rain and hail were reported. 2/9/2015
A strong winter storm impacted California following up the driest January on record. The storm brought heavy rain, winds, and damage to trees and power lines along with some minor flooding. The County gauge on Three Peaks at Elevation 3362 feet measured a 72-hour rainfall total of 10.4 inches.
12/11/2014
An atmospheric river brought a storm with heavy rain and winds. Boats in Monterey Harbor had to be pumped out to avoid sinking. Rain overwhelmed a sewage plant in Castroville causing a spill. 11/30/2012
A series of significant winter storms brought strong and gusty winds, heavy rainfall, high surf. Minor urban and small stream flooding was observed across Monterey County due to the heavy rainfall. 1/1/2011
A storm system brought strong gusty winds and heavy rain. A large tree fell on an occupied vehicle causing the closure of State Route 183 in Monterey.
1/20/2010
The third in a series of storms brought strong winds and heavy rain. An intense hailstorm occurred near Ryan Ranch just southeast of Del Rey Oaks.
Source: NOAA Storm Events Database
Windstorm
A windstorm in October 2009 was the result of a strong low-pressure system caused an estimated $1 million in damage, mainly due to falling trees hitting cars and buildings in the affected area. A wind event from November 2011 caused damage and one fatality in Big Sur due to a falling tree. In addition to winter windstorms, every year, between the months of March and October, when the Pacific High attains its greatest strength, prevailing northwest sustained surface winds in Salinas Valley reach average speeds of 10 to 15 mph with associated wind gusts up to 45 mph.
The County has also recorded five tornadoes between 1950 and 2020. All five tornadoes occurred in the northeastern portion of Monterey County. The largest tornado, occurred in 1992, reaching a magnitude of F1 (maximum wind speeds of 73–112 mph) resulted in two injuries from flying glass.
Extreme Heat
In October 2012, an unseasonable heat wave gripped the Monterey area. Temperatures soared well into the 90s and 100s, which resulted in all-time record high temperatures for October, reaching 100 and 101 in Salinas. Farm workers who were picking in the fields near Salinas were negatively impacted by the excessive heat, which lead to a fatality of a farm worker on October Packet Page 439
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2. In July of 2006, intense heat settled over the County with temperatures soaring to as high as 115°F. Temperatures exceeded 100°F for 15 consecutive days in July, with high temperatures soaring to over 110°F. Overnight lows stayed in the mid-60s for several nights.
14.2.2 LOCATION
All severe weather events profiled in this assessment have the potential to happen anywhere in the County. Maps of the average distribution of weather conditions were used to provide an indication of which areas may be more vulnerable to different severe weather hazards.
Severe Winter Storms
As seen in Figure 14-2, higher annual precipitation occurs along the Big Sur coast, in the Del Monte Forest, and in the hills above the Salinas Valley. These areas therefore may be more likely to experience heavy rain during a winter storm. Communities in low lying areas next to streams, lakes, or the ocean are likely more susceptible to flooding following heavy rain events.
Figure 14-2
30-Year Average Annual Precipitation in Monterey County Figure 14-2: 30-Year Average Annual Precipitation in Monterey County Packet Page 440
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Extreme Cold and Freeze
Exposure to extremely cold temperatures varies depending on distance from the coast and elevation. Coastal temperatures are lower, while inland and higher elevation areas experience a greater range of temperatures. Historically extreme freeze events have been most frequently experienced in the mountains and interior valleys in the County, notably the Southern end of the Salinas Valley.
As seen in Figure 14-3, mountainous areas of the County, including the Santa Lucia and Gabilan Ranges, areas along the Big Sur Coast, and the Southern portion of the Salinas Valley experience the coldest average temperatures. These areas therefore may be more likely to experience colder than average temperatures during extreme cold and freeze events.
Figure 14-3
30-Year Average Minimum Temperatures in Monterey County Figure 14-3: 30-Year Average Minimum Temperatures in Monterey County Windstorm
The Monterey Bay acts as a funnel, channeling ocean air through the Salinas Valley. Warmer air from the southern end of the valley warms and rises, producing pressure that in its turn draws in cooler air from Monterey Bay. The wind created as a result is shifted from the broad expanse Packet Page 441
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of the Bay through the narrower Salinas Valley. The geographical constriction produces a decrease in air pressure, which correspondingly increases the flow of cold ocean air across the valley.
As seen in Figure 14-4, the fastest wind speeds occur in the Salinas Valley. Portions of the Peninsula, Carmel Highlands, and Monterey Bay may also experience high winds. Wind events are likely to be most damaging in areas that are heavily wooded.
Figure 14-4
Land-Based Wind Speed (Meters/Second)
Figure 14-4: Land-Based Wind Speed (Meters/Second)
Extreme Heat
Proximity to extreme heat varies depending on distance from the coast and elevation. Coastal temperatures are lower, while inland and higher elevation areas experience a greater range of temperatures. The inland regions of the County have historically been the most likely to experience high heat conditions.
As seen in Figure 14-5, areas of South County, the lower Salinas Valley, and mountainous areas in the southern region of the County, including the Santa Lucia and Gabilan Ranges are the Packet Page 442
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most prone to high temperatures and are the area’s most likely to experience extreme heat or heat waves.
Figure 14-5
30-Year Average Maximum Temperatures in Monterey County Figure 14-5: 30-Year Average Maximum Temperatures in Monterey County
14.2.3 FREQUENCY
Predicting the frequency of severe weather events in a constantly changing climate is a difficult task. The County can expect to experience exposure to and adverse impacts from some type of severe weather event at least annually. Severe storms and rainfall are limited almost entirely to the winter season (November - April), while extreme heat is mostly limited to summer months.
The FEMA National Risk Index calculates an annualized frequency value for certain natural hazards in Monterey County. The natural hazard annualized frequency was defined by FEMA as the expected frequency or probability of a hazard occurrence per year. Annualized frequency was derived either from the number of recorded hazard occurrences each year over a given period or the modeled probability of a hazard occurrence each year. Since most severe weather Packet Page 443
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hazards have tracked actual hazard occurrences, annualized frequency was based on either the number of distinct hazard events that have occurred or the count of days on which a hazard has occurred.
Table 14-2 summarizes the annualized frequency values and hazard occurrence basis (event or event-day) provided by the FEMA National Risk Index for the severe weather hazards that were included in the Index.
Table 14-2: Annualized Frequency of Severe Weather Events in Monterey County Table 14-2
Annualized Frequency of Severe Weather Hazards in Monterey County Hazard Hazard Occurrence Basis Annualized Frequency
Hail Distinct Events 0.47 Events per Year
Heat Wave Event-Days 1.21 Event Days per Year
Lightning Distinct Events 0.36 Events per Year
Strong Wind Distinct Events 0.13 Events per Year
Tornado Distinct Events 1.22 Events per Year
Winter Weather Event-Days 0.07 Event Days per Year
Source: FEMA National Risk Index
14.2.4 SEVERITY
Severe Winter Storms
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, 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.
Heavy rain can have significant impacts, including flash flooding, mudslides, and landslides.
Stormwater runoff from heavy rains can also impair water quality by washing pollutants into water bodies. Thunderstorms carry the same risks as heavy rain events, and depending on the type of storm, they can also include tornados, lightning, and heavy winds, increasing risk of injury and property damage. Lightning strikes are a danger during thunderstorms and can cause death or injury to one or several persons. Long-term injuries from lightning strike can include memory and attention loss, chronic numbness, muscle spasm, stiffness, depression, hearing loss and sleep disturbance.
Extreme Cold and Freeze
Late or early freeze events can have a devastating effect on agriculture and the economy of the region. Crops can be damaged by below-freezing temperatures. Prolonged exposure to cold can cause frostbite or hypothermia and can be life-threatening. Infants and the elderly are most susceptible. Pipes may freeze and burst in homes or buildings that are poorly insulated or without heat.
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Windstorms
Windstorms are a frequent problem in the County 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% higher. Tornadoes are potentially the most dangerous of local storms, but they are not common. If a major tornado were to strike within the populated areas of the County, damage could be widespread. Businesses could be forced to close for an extended period or permanently, fatalities could be high, many people could be homeless for an extended period, and routine services such as telephone or power could be disrupted. Buildings may be damaged or destroyed.
Extreme Heat
Extreme heat is the primary weather-related cause of death in the US Extreme heat can kill by taxing the human body beyond its abilities. Since heat affects everybody differently and to better address heat risk the National Weather Service (NWS) developed an experimental HeatRisk forecast, which provides one value each day that indicates the approximate level of heat risk concern for any location, along with identifying the groups who are most at risk.
The scale is summarized in Table 14-3.
Table 14-3: NWS Experimental HeatRisk Forecast Risk Levels Table 14-3
NWS Experimental HeatRisk Forecast Risk Levels
Category Level Meaning
Green 0 No Elevated Risk
Yellow 1 Low Risk for those extremely sensitive to heat, especially those without effective cooling and/or adequate hydration
Orange 2 Moderate Risk for those who are sensitive to heat, especially those without effective cooling and/or adequate hydration
Red 3 High Risk for much of the population, especially those who are heat sensitive and those without effective cooling and/or adequate hydration Magenta 4 Very High Risk for entire population due to long duration heat, with little to no relief overnight
Heat can cause a variety of health-related issues including:
• Heat Exhaustion: Heat exhaustion is a mild form of heat-related illness that can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids. It is the body’s response to an excessive loss of the water and salt contained in sweat. Those most prone to heat exhaustion are elderly people, people with high blood pressure, and people working or exercising in a hot environment. • Heat Cramps: Heat cramps usually affect people who sweat a lot. Sweating depletes the body’s salt and moisture. The low salt level in the muscles can cause heat cramps. Heat cramps may also be a symptom of heat exhaustion.
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• Heat Stroke: Heat stroke is a severe, dangerous form of heat-related illness. It occurs when the body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Body temperature may rise to 106°F or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability.
14.2.5 WARNING TIME
Meteorologists can often predict the likelihood of a 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 Monterey Weather Forecast Office of the NWS monitors weather stations and issues watches and warnings when appropriate to alert government 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.
14.3 SECONDARY HAZARDS
The most significant secondary hazards associated with severe local storms are floods, falling and downed trees, mudslides, 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 become oversaturated and fail. As noted previously, for information on the impacts of hazards related to severe weather, refer to Flooding in Section 10, Slope Failure in Section 15, and Utility Interruption in Section 17.
14.4 RISK ASSESSMENT
A lack of clearly defined extent and location mapping for the severe weather hazards profiled in this chapter prevented a detailed analysis for exposure and vulnerability. However, it can be assumed that the entire County is exposed to some extent to the severe weather hazards profiled in this assessment. Certain areas are more exposed due to geographic location and local weather patterns.
The FEMA National Risk Index calculates exposure and annual expected loss of building value and population for some severe weather hazards in Monterey County. Though the entire County is considered vulnerable to these hazards, the FEMA data was used in this risk assessment to provide some scale for the potential risk and impacts.
14.4.1 POPULATION
Population exposed in Monterey County to severe weather based on the FEMA National Risk Index is summarized in Table 14-4.
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Table 14-4: Population Exposed to Severe Weather Hazards in Monterey County Table 14-4
Population Exposed to Severe Weather Hazards in Monterey County Hazard Exposed Population
Hail 415,057
Heat Wave 413,337
Lightning 415,057
Strong Wind 415,057
Tornado 85
Winter Weather 12,879
Source: FEMA National Risk Index
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 following severe winter storms.
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.
14.4.2 PROPERTY
All property is vulnerable during the severe weather events profiled in this chapter. Building value exposed and the expected annual loss of building value in Monterey County to severe weather based on the FEMA National Risk Index is summarized in Table 14-5.
Table 14-5: Exposed and Expected Annual Loss of Building Value to Severe Weather Table 14-5
Exposed and Expected Annual Loss of Building Value to Severe Weather Hazards Hazard Exposed Building Value Expected Annual Loss- Building Value Hail $41,169,506,000 $1
Heat Wave $40,973,571,144 $72
Lightning $41,169,506,000 $5,966
Strong Wind $41,169,506,000 $16,331
Tornado $8,429,968.67 $204,827
Winter Weather $2,219,002,076 $4,195
Source: FEMA National Risk Index
Properties in poor condition or in particularly vulnerable locations may be at risk of 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. Extreme heat events are not known for Packet Page 447
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causing direct damage to buildings, but may damage building systems such as heating, ventilation, and air conditioning systems.
14.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
All critical facilities are likely exposed to all of the severe weather hazards profiled in this assessment. The most common problems associated with severe weather are loss of utilities.
Prolonged periods of extreme heat could result in power outages caused by increased demand for power for cooling. Downed power lines associated with wind and/or thunderstorm events can cause blackouts, leaving large areas isolated. Phone, water, and sewer systems may not function. Roads may become impassable due to secondary hazards such as mudslides and landslides.
14.4.4 ENVIRONMENT
The environment is highly exposed to severe weather events profiled in this assessment.
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. Flood 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. Vegetation can die as a result of prolonged periods of extreme heat.
14.4.5 ECONOMIC IMPACT
Economic impact of a severe storm is typically short term. Lightning can cause power outages and fires. Hail can destroy exposed property; an example is car lots, where entire inventories can be damaged. Generally, long-term economic impacts center more around hazards that cascade from a severe thunderstorm, including wildfires ignited by lightning, and flooding. In general, all severe weather poses a risk to the agriculture economy in the County.
14.5 FUTURE TRENDS IN DEVELOPMENT
All future development will be affected by severe storms, extreme heat, and high winds. The ability to withstand impacts lies in sound land use practices and consistent enforcement of codes and regulations for new construction. New critical facilities, such as communication towers should be built to withstand heavy rain, wind, and hail damage. Future development projects should consider adverse weather hazards at the planning, engineering, and architectural design stage with the goal of reducing vulnerability. Stormwater master planning and site review should account for buildings to withstand adverse weather events considered for all new development. Thus, development trends in the County are not expected to increase overall vulnerability to the hazard but all development will be affected by adverse weather and storm events and population growth will increase potential exposure to hazards such as thunderstorms and dense fog.
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14.6 ISSUES
Important issues associated with a severe weather in Monterey County include the following:
• Older building stock in the County 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 centers during extreme heat 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.
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15. SLOPE FAILURE
15.1 OVERVIEW
The term “slope failure” describes a wide variety of processes that result in the downward and outward movement of slope-forming materials including rock, soil, artificial fill, or a combination of these. The materials may move by falling, toppling, sliding, spreading, or flowing. Slope failure can range from slow moving rotational slumps and earth flows, which can slowly distress structures but are less threatening to personal safety, to fast-moving rock avalanches and debris flows that are a serious threat to structures and have been responsible for most fatalities during landslide events.
Slope failure occurs when the strength of the soils forming the slope is exceeded by pressure, such as weight, gravity, or saturation. This can be initiated by storms, earthquakes, fires, or human modification of the land. Large debris can block transportation routes, dam creeks and drainages, and contaminate water supplies. When these hazards affect transportation routes, they are frequently expensive to clean-up and can have significant economic impacts.
15.1.1 TYPES OF SLOPE FAILURE
The various types of slope failure can be differentiated by the kinds of material involved and the mode of movement. The term encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material.
Falls: Falls are abrupt, downward movements of rock or earth, or both, that detach from steep slopes or cliffs. Falls are triggered by the undercutting of the slope by natural processes such as Packet Page 451
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streams and rivers or differential weathering, human activities such as excavation during road building and/or maintenance, and earthquake shaking or other intense vibration. Steep or vertical slopes, particularly in coastal areas, and along rocky banks of rivers and streams are susceptible to falls.
Topple: A topple is the forward rotation out of a slope of a mass of soil or rock. Toppling is driven by gravity exerted by the weight of material upslope from the displaced mass or is due to cracks in the mass. Topples can consist of rock, debris, or earth materials.
Slides: A slide is a mass movement of soil or rock occurring where there is a distinct zone of weakness that separates the slide material from more stable underlying material. Slides can be triggered by intense and/or sustained rainfall or rapid snowmelt which can saturate slopes.
Rapid drops in river level following floods, ground-water levels rising because of filling reservoirs, or the rise in level of streams, lakes, and rivers, which cause erosion at the base of slopes. Slides can also be earthquake induced.
Spreads: Lateral spreads are distinctive because they usually occur on very gentle slopes or flat terrain. The dominant mode of movement is lateral extension accompanied by shear or tensile fractures. The failure is caused by liquefaction, the process whereby saturated, loose, cohesionless sediments (usually sands and silts) are transformed from a solid into a liquefied state. Failure is usually triggered by rapid ground motion, such as that experienced during an earthquake, but can also be artificially induced.
Flows: A form of rapid mass movement in which loose soil, rock and sometimes organic matter combine with water to form a slurry that flows downslope.
Debris flows, rockslides, and flood flows will be described in more detail in this plan as they the most likely to occur in Monterey County.
Debris Flows
Debris flows are common types of fast-moving landslides in Monterey County. These flows generally occur during periods of intense rainfall. They usually start on steep hillsides as shallow landslides that liquefy and accelerate to speeds that are typically about 10 mph, but can exceed 35 mph. The consistency of debris flows ranges from watery mud to thick, rocky mud that can carry large items such as boulders, trees, and cars. They are particularly dangerous to life and property because of their high speeds and the sheer destructive force of their flow.
Debris flow risk in the County is primarily associated with burn scars. Vegetation and soil changes after a fire increase the runoff and erosion in a watershed, and significantly increase the likelihood of debris flows. Debris flows can initiate during even moderate rainstorms over burn areas and often occur with little warning. Post-fire flow can alternate between flood and debris flow. It is important to distinguish between flood flows and debris flows as both are risks in the County. Distinguishing between debris flow and flood deposits can be difficult, but certain sedimentary structures and textures can give clues to the mechanism of deposition.
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Debris flows are more dangerous and more destructive and dangerous than floods because they often have peak discharge levels that are 10-50 times greater. Flow height can be up to 5 times greater with flow velocity that is flow velocity same or greater. They also contain much higher levels of sediment content which can cause faster and more uncontrollable flows.
Flood Flows
A flood flow differs from a flood in that the amount of suspended sediment is sufficient to significantly change fluid properties and sediment transport mechanisms. Large volumes of sand are transported in dynamic suspension throughout the water column, although maintenance of high sediment loads depends on flow velocity and turbulence. Flows can be highly erosive.
Rockslides
A rockslide, common along the Big Sur coast, is a slow-moving or “creeping” landslide in weathered, fractured, or otherwise-weakened rock. Movement on deep-seated rockslides typically is only fractions of an inch per year; however, an increase in rainfall or slope instability can accelerate movement to several yards a minute or faster.
15.1.2 SLOPE FAILURE CAUSES
Mass movements are caused by a combination of geological and climate conditions, as well as encroaching urbanization. Vulnerable natural conditions related to the geology, topography, and vegetation are affected by residential, agricultural, commercial, and industrial development and the infrastructure that supports it. Relative susceptibility to landslides can be described according to the following geologic conditions:
• Low: Flatlands and low relief terrain, includes mainly Quaternary deposits. In steep terrain, includes mainly crystalline basement rock, volcanic rock, and Cretaceous sandstone.
• Moderate: Moderately steep terrain underlain by mainly unconsolidated and weakly cemented sandstone, shale, and Franciscan Complex.
• High: Steep terrain underlain by mainly unconsolidated and weakly cemented sandstone, shale, Franciscan Complex, and existing landslides.
The factors that can contribute to slope failure include: Change in slope of the terrain; Increased load on the land; Shocks, vibrations, and earthquakes; Change in water content; Groundwater movement; Frost action; Weathering of rocks and erosion; Removing or changing the type of vegetation covering slopes.
Landslides can be initiated in slopes already on the verge of movement by rainfall, snowmelt, changes in water level, stream erosion, changes in ground water, earthquakes, volcanic activity, disturbance by human activities, or any combination of these factors. Earthquake shaking and other factors can also induce landslides underwater. These landslides are called submarine landslides. Submarine landslides sometimes cause tsunamis that damage coastal areas.
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15.2 HAZARD PROFILE
15.2.1 HISTORY
Big Sur Coastline
The Big Sur area is one of the most landslide-prone
stretches of the California coast, with over 1,500
mapped historic large landslides. Table 15-1
summarizes the most destructive landslides that have
occurred along the Big Sur coast.
Historically, landslide activity has increased during
severe El Niño years. During the 1972–1973 El Niño
season, a landslide along the Big Sur coast resulted in one death. Throughout the 1997–1998 El Niño season,
Highway 1 closed all along the Big Sur Coast due to
flooding and mudslides and about 40 different
sections of the highway were damaged.
In more recent year’s numerous landslide events have
been recorded in Big Sur, damaging structures, and
forcing the closure of Highway 1. 2017 saw record
damage along Highway 1. In February, a column of the
Pfeiffer Canyon Bridge was displaced by an active
landslide, which moved eight inches in one night and
destabilized the bridge. This section of Highway 1 was
closed for eight months and the new bridge cost
about $24 million.
In March of 2017, Paul’s Slide buried Highway 1 with
debris and left only 11 feet of roadway. Around 2
million cubic yards of material came down the hill. In
May, at Mud Creek, a deep-rooted debris flow caused
by the heavy winter rains, covered a quarter mile of
the Highway 1 in 6 million cubic yards of debris, close to 40 feet of debris slid down the hillside. Caltrans
rebuilt the highway atop the slide in a $54 million, 14- month project.
In 2021, an atmospheric river resulted in a post-fire debris flow washing out a 150-foot-long stretch of Highway 1 near Rat Creek below the Dolan Fire burn scar. Flows also damaged another 60 locations along the highway.
Mitigation Success Story
Rain Rocks Shed/Pitkin’s Curve Bridge
Landslides repeatedly damaged Highway 1
at Pitkins Curve and Rain Rocks.
The Rain Rocks Shed/Pitkin’s Curve Bridge is
an innovative mitigation strategy. The new
bridge and shed allow rocks to keep rolling.
This is a unique and sustainable solution to
what was once an ongoing problem. Though
the project cost $39 million, over the 50-year
lifespan the cost of maintaining the highway
with the new structures is estimated at $1.7
million, while it would have cost
about $112 million
to maintain the
highway without
the project.
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Table 15-1: Historic Large Landslides Along Highway 1 on the Big Sur Coast Table 15-1
Historic Large Landslides Along Highway 1 on the Big Sur Coast, Monterey County Location Date Event Event Narrative Cost
Big Sur 3/1/1983 Landslide
A series of storms caused four major
slides between January and April. A slide
in March, near Julia Pfeiffer Burns State
Park, was at the time the largest slide to
affect Hwy 1.
$10 million
Gorda 1/2/1997 Landslide A landslide near Gorda, closed Hwy 1 for one month.
$5.5
million
Big Sur 2/6/1998 Mudslide
El Niño storms caused severe damage to
Hwy 1. About 40 sections of Hwy 1 were
affected by flooding and landslides.
$32 million
Gorda 2/14/2000 Landslide
Hwy 1 at Pitkin’s Curve was closed due
to a landslide that took out both lanes
and created 7,000 truckloads of debris. A
secondary landslide occurred during
repair in March.
$3.4
million
Big Sur 2/1/2001 Landslide
A landslide above Pitkin’s Curve
disrupted traffic for 2 months, requiring
removal of 1,400 truckloads of debris.
$1.5
million
Big Sur 11/1/2008 Landslide
Heavy rain following the Basin Complex
fire resulted in debris flows and flash
flooding. A foot bridge, 2 fishponds, and
2 residences were damaged by a 6-foot
debris flow.
Big Sur 4/7/2009 Debris
Flow
Heavy rain on the Basin-Complex burn
scar, caused flash flooding and debris
flows. At least 3 separate debris flows
were reported along Hwy 1. At Big Sur
Lodge, vehicles were stuck in mud, and
one was forced into a culvert and buried.
Big Sur 3/16/2011 Landslide
Heavy rain in Big Sur washed out a 40 ft
section of Hwy 1 section near the Bixby
Creek Bridge and Rocky Creek.
$2.5
million
Gorda 4/14/2011 Landslide
A rock and mudslide closed Hwy 1 near
Alder Creek. The initial small slide was
cleared, but the storms from March
provided the necessary moisture to
cause the hillside to fail weeks later,
producing another much debris flow
later in April.
$5 million
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Table 15-1
Historic Large Landslides Along Highway 1 on the Big Sur Coast, Monterey County Location Date Event Event Narrative Cost
Posts 12/22/2012 Debris
Flow
An atmospheric river caused several
slides, including one at Partington Creek
that blocked Hwy 1 and a private road.
32 homes were isolated, and 40 tourists
were stranded.
Posts 2/9/2017 Debris
Flow
A slide closed Hwy 1 and displaced a
column of the Pfeiffer Canyon Bridge,
moving 8 inches in one night and
destabilizing the bridge. Caltrans
determined it was unrepairable and
closed the road for 8 months to build a
new bridge.
$24 million
Lucia 3/11/2017 Landslide
Paul’s Slide buried Hwy 1 with 2 million
cubic yards of debris leaving only 11 ft of
roadway. 435 residents were caught
between the slide and the closure at
Pfeiffer Canyon Bridge.
Gorda 5/19/2017 Debris
Flow
A deep-rooted debris flow at Mud Creek,
covered a quarter mile of the Hwy 1 in 6
million cubic yards of debris.
$54 million
Lucia 1/27/2021 Debris
Flow
An atmospheric river washed out a 150-
foot-long stretch of Hwy 1 near Rat
Creek below the Dolan Fire burn scar.
Flows damaged another 60 locations
along the highway.
Sources: NOAA Storm Events Database; A History of Road Closures Along Highway 1, Big Sur Monterey and San Luis Obispo Counties, California
Historic Slope Failure in Other Geographic Regions
Besides the Big Sur coastline other areas of the County are vulnerable to debris flows.
Throughout the 1997–1998 El Niño season, a series of debris slides failed along the northern flank of Saddle Mountain in Carmel Valley and impacted Saddle Mountain Recreation Area. A landslide in Las Lomas in rural north Monterey County caused several homes to be destroyed and resulted in a Hazard Mitigation Grant Program (HMGP) project that involved buying out the affected homes and preserving the land where the slide occurred as perpetual open space.
The 2017 storms caused flooding and debris flows in Prunedale and Spreckels resulting in mud, and rocks covering various sections of roadway, including Crazy Horse Canyon Road, Live Oak Road, Garin Road, and Elkhorn Road. Highway 101 was blocked at Crazy Horse Canyon Road and Highway 68 was blocked with over 1 foot of mud at River Road. One heavy slide caused Packet Page 456
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mud, about 3 feet deep, to block Moro Road. In 2019, heavy rainfall caused large rocks to block Carmel Valley Road at Laureles Grade. In 2021 an annual expected storm caused a large debris flow in the River Fire burn scar. The flow damaged 25 homes and caused one injury.
15.2.2 LOCATION
The best available predictor of where 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.
Debris and sediment flows are a particular threat to life and property in mountainous areas of Monterey County. Areas of highest susceptibility to large landslides include Carmel Valley, the Arroyo Seco district, and the foothills of southern Salinas Valley. In this area, rocks have been weakened through faulting, fracturing, and uplift, and are vulnerable to earthquake or rain induced landslides.
Landslides are most common along the steep slopes of the Big Sur coast. Recurrent uplift, in combination with relentless erosion by ocean waves, creates extreme topography, making the area highly susceptible to landslides. Rocks that have been weakened through faulting and fracturing also help provide ideal conditions for large landslides. During the winter months, Big Sur receives both heavy rainfall (as much as 80 inches per year) and high wave energy. In summer and fall, occasional wildfires remove vegetation, making the areas slopes more vulnerable to erosion. All these factors produce chronic landslides, such as those that block, undermine, or damage the Coast Highway.
The potential for debris flows increases significantly in areas recently burned by large wildfires.
Wildfires can greatly reduce the amount of vegetation, which reduces the ability for the ground to absorb rainwater, allowing excessive water runoff that can include large amounts of debris.
An area of current particular concern is the burn scars of the 2020 Dolan, River, and Carmel fires. While post-fire assessment data and detailed mapping on vulnerability to debris flow is not available, structures located anywhere near the burn area should be considered potentially at risk during and following high intensity rainfall events until the vegetation is restored.
The California Geological Survey maps the relative likelihood of deep land sliding based on regional estimates of rock strength and steepness of slopes. On the most basic level, weak rocks and steep slopes are more likely to generate landslides. Their mapping uses detailed information on the location of past landslides, the location and relative strength of rock units, and steepness of slope.
This mapping shows the distribution of landslide hazards and provides an overview of where landslides are more likely. This mapping does not include information on landslide triggering Packet Page 457
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events, such as rainstorms or earthquake shaking, nor does it address susceptibility to shallow landslides such as debris flows and is not appropriate for evaluation of landslide potential at any specific site.
Mapping of deep-seated landslide susceptibility in Monterey County based on data from the California Geological Survey 65 is shown in Figure 15-1.
Figure 15-1
Deep-Seated Landslide Susceptibility in Monterey County Figure 15-1: Deep-Seated Landsilde Susceptibility in Monterey County Additionally, areas in the County are susceptible to earthquake induced landslides. Figure 15-2 shows earthquake induced landslide susceptibility in Monterey County. 65 CGS Map Sheet 58: Deep-Seated Landslide Susceptibility, California Geological Survey (May 2011) Packet Page 458
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Figure 15-2: Earthquake Induced Landslide Susceptibility Packet Page 459
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15.2.3 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 Monterey County, landslides typically occur during and after severe storms, so the potential for landslides largely coincides with the potential for sequential severe storms that saturate steep, vulnerable soils. The FEMA National Risk Index estimates that the annualized frequency of landslide events in Monterey County is 0.43 distinct events per year.
In general Monterey County can expect to experience significant landslide events during strong El Niño years, large atmospheric rivers, or during a large earthquake event. In areas recently burned by wildfires, landslides may occur more frequently and are possible during annual rain events.
15.2.4 SEVERITY
Slope failures destroy property and infrastructure and can take the lives of people. 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.
Slope failure can pose a serious hazard to properties on or below hillsides. They can block access to roads, which can isolate residents and businesses and delay commercial, public, and private transportation. This can result in economic losses for businesses. Vegetation or poles on slopes can be knocked over, resulting in possible losses to power and communication lines.
Slope failures can also damage rivers or streams, potentially harming water quality, fisheries, and spawning habitat.
In Monterey County, landslides and mudslides are a common occurrence and have caused damage to homes, public facilities, roads, parks, and sewer lines. Landslides along the county’s coastline, in conjunction with wave action, have resulted in road failure, severe erosion, cliff failure, and loss of bluff top area that threatens development. In Big Sur, landslides have caused millions of dollars in damages and have led to closures of Highway 1, which can range from a few days to over a year.
15.2.5 WARNING TIME
The velocity of landslides ranges from a slow creep of inches per year to many feet per second, depending on slope angle, material, and water content. Some types of slope failure, occur slowly but can have significant property or health consequences. The identification of those hazards generally takes site-specific analysis to determine if the site soils and geology are susceptible to these hazards and what mitigation is most relevant and prudent for a site. For these types of hazards, warning time is long.
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For other hazards, such as debris flows, rockfalls, and landslides, warning time is often very short and may not occur at all. Identifying areas where these events are known have occurred, or which have ideal characteristics for these hazards to occur, could help with hazard preparedness when triggering-type events like intense rainfall occur.
Some methods used to monitor landslides can provide an idea of the type of movement and the amount of time prior to failure. It is also possible to determine what areas are at risk during general time periods. Assessing the geology, vegetation, and amount of predicted precipitation for an area can help in these predictions. However, there is no practical warning system for individual landslides.
When wildfire-induced landslide threats exist a state team of foresters, hydrologists, and GIS specialists from CAL FIRE, engineering geologists from the California Geological Survey (CGS) and Regional Water Quality Control Boards (RWQCB), and civil engineers from the Department of Water Resources (DWR), can be assembled into a Watershed Emergency Response Team (WERT) to assess potential life-safety hazards from post-fire debris flows, hyper-concentrated flows, and flood flows on Local and State Responsibility Areas.
An Emergency Stabilization-Burned Area Emergency Response (BAER) is a rapid assessment of burned watersheds that identifies imminent post-wildfire threats to human life and safety, property, and critical natural or cultural resources on federal land. The BAER identifies emergency stabilization measures that can be implemented before the first post-fire damaging events. BAER measures include actions such as: mulching, seeding, installation of erosion and water run-off control structures, temporary barriers to protect recovering areas, and the installation of warning signs.
The USGS also conducts post-fire debris-flow hazard assessments for select fires using geospatial data related to basin morphometry, burn severity, soil properties, and rainfall characteristics to estimate the probability and volume of debris flows that may occur in response to a storm. This identification and analysis will not reduce the warning time, but it will make proactive response to potential triggering events more effective.
15.3 SECONDARY HAZARDS
There are some hazards that can trigger or exacerbate slope failure. Flooding, for example, can undercut the toe of a slope which can remove the support for the slope and cause a landslide.
Wildfires create long-term impacts by altering the soil structure, impeding its ability to absorb moisture, and destroying vegetation that binds the soil with roots and absorbs rainfall and runoff. Post-wildfire, even small rainfall events can cause devastating landslides. Areas that are mapped currently as low to moderate risk of these hazards may have high risk after a wildfire.
Landslides can cause several types of secondary effects, such as blocking access to roads, which can isolate residents and businesses and delay commercial, public, and private transportation.
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This could result 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.
15.4 RISK ASSESSMENT
Data developed for the Monterey County 2010 General Plan Update - Relative earthquakeinduced landslide susceptibility of Monterey County (Lewis Rosenberg) - was used to assess earthquake induced slope failure risk in Monterey County.
Additionally, data from the FEMA National Risk Index was used to capture a wider swath of slope failure risk.
15.4.1 POPULATION
The FEMA National Risk Index estimates that a population of 79,208 people is exposed to landslide risk in Monterey County. As summarized in Table 15-2, close to 90,000 people are exposed to high or moderate earthquake induced landslide risk in Monterey County.
Table 15-2: Population Exposed to Earthquake Induced Landslide Risk Table 15-2
Population Exposed to Earthquake Induced Landslide Risk in Monterey County Supervisorial District High Moderate
District 1 0 0
District 2 10,603 20,284
District 3 3,940 4,109
District 4 307 760
District 5 18,752 28,902
Total 33,602 54,055
Increasing population and the fact that many homes are built on view property atop or below bluffs and on steep slopes subject to failure, increases the number of lives endangered by this hazard. Populations with access and functional needs as well as elderly populations and the young are more vulnerable to the landslide hazards as they may not be able to evacuate quickly enough to avoid the impacts of a landslide.
15.4.2 PROPERTY
The FEMA National Risk Index estimates that $10,420,650,330 of building value in Monterey County is exposed to landslide risk. On average, $16,721 in building value is exposed annually to landslide risk.
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As summarized in Table 15-3, about 10,000 residential properties, around $9 billion in value, is exposed to high or moderate earthquake-induced landslide risk in Monterey County.
Table 15-3: Residential Property Exposed to Earthquake Induced Landslide Risk Table 15-3
Residential Property Exposed to Earthquake Induced Landslide Risk in Monterey County Supervisorial
District
High Moderate
# Value # Value
District 1 0 $0 0 $0
District 2 255 $121,610,859 2,985 $1,462,850,110
District 3 402 $111,813,559 587 $168,618,666
District 4 0 $837,871 129 $61,419,691
District 5 1,889 $2,237,652,534 4,665 $5,235,107,467
Total 2,546 $2,471,914,823 8,366 $6,927,995,934
As summarized in Table 15-4, close to 11,000 non-residential properties, around $3 billion in value, is exposed to high or moderate earthquake-induced landslide risk in Monterey County.
Table 15-4: Non-Residential Property Exposed to Earthquake Induced Landslide Risk Table 15-4
Non-Residential Property Exposed to Earthquake Induced Landslide Risk in Monterey County Supervisorial
District
High Moderate
# Value # Value
District 1 0 $0 0 $0
District 2 170 $42,267,723 1,604 $205,569,876
District 3 2,714 $882,625,037 3,298 $1,067,573,258
District 4 7 $0 38 $10,636,707
District 5 1,196 $472,577,390 2,039 $1,025,327,227
Total 4,087 $1,397,470,150 6,979 $2,309,107,068
15.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
A significant amount of linear infrastructure and critical lifelines are exposed to slope failure.
Access to major roads is crucial to life-safety, response, and recovery operations after a disaster event. Slope failure events can block egress and ingress on roads, causing isolation for neighborhoods, traffic problems, and delays for public and private transportation. This can result in economic losses for businesses. Slope failure can significantly impact bridges, by knocking out bridge abutments or significantly weaken the soil supporting them. Highly susceptible areas of the County include mountain and coastal roads and transportation infrastructure.
Power lines are generally elevated above steep slopes, but the towers supporting them can be subject to slope failure. A landslide could trigger failure of the soil underneath a tower, causing it to collapse and rip down the lines. Power and communication failures due to landslides can create problems for vulnerable populations and businesses Packet Page 463
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Critical infrastructure determined to be exposed to earthquake-induced landslide risk is summarized in Table 15-5.
Table 15-5: Critical Infrastructure Exposed to Earthquake Induced Landslide Risk Table 15-5
Critical Infrastructure Exposed to Earthquake Induced Landslide Risk in Monterey County Critical Infrastructure Type High Moderate
Facilities
Emergency Response 2 1
Fire Station 2 3
Police Station 0 0
Medical Facilities 0 2
Military Facility 0 0
Large Public Facilities 0 0
Educational Facilities 0 2
Power Plant 0 0
Water & Wastewater Facilities 11 53
Stormwater Facilities 0 0
Government Facilities 6 9
Communication Facilities 142 205
Rain Gauges 2 3
Lighthouses 0 0
Dams 0 0
Hazardous Materials
Active or Idle Oil Well 268 822
Landfill 0 0
Underground Tank 0 2
Cal ARP Facility 0 0
Transportation
Airport 0 0
Bridge 8 9
Harbor 0 0
Highway/Freeway (Miles) 2 26
Driveway (Miles) 0 3
Major Road (Miles) 192 278
Local (Miles) 780 780
Railroad (Miles) 10 10
15.4.4 ENVIRONMENT
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 prolonged periods of time due to landslides. Disposal of landslide debris into the Monterey Bay National Marine Sanctuary (MBNMS) could damage critical marine habitats.
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15.4.5 ECONOMIC IMPACT
Millions of visitors travel annually along the Highway 1 in Big Sur, bringing many millions of dollars to the local economy. Maintaining safe access along the Highway is essential for both tourism and the livelihood of residents. Landslides in Big Sur frequently damage the popular and economically essential Highway 1 and can close the road for weeks or months at a time.
Maintenance of the highway is expensive and controversial.
15.5 FUTURE TRENDS IN DEVELOPMENT
Land use controls (such as prohibiting development on unstable soils or steep slopes) are the most cost-effective way to prevent loss of life and property. The planning partners are equipped to handle future growth within landslide hazard areas. Landslide risk areas are addressed in the safety elements of local general plans. The State of California has adopted the International Building Code (IBC) by reference in its California Building Standards Code. The IBC 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.
15.6 ISSUES
Key issues related to slope failure in Monterey County include:
• There are existing homes in landslide risk areas throughout the County. 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. • The impact of landslides on tourism in Big Sur.
• 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.
• 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.
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16. TSUNAMI
16.1 OVERVIEW
A tsunami is a wave or series of waves, caused by a displacement of the ocean floor, generated by an earthquake, landslide, volcanic eruption, or even large meteor hitting the ocean. What typically happens is a large, submarine earthquake (magnitude 8 or higher) creates a significant upward movement of the sea floor resulting in a rise or mounding of water at the ocean surface. The mound of water moves away from this center in all directions as a tsunami. These events are also often referred to as tidal waves or seismic sea waves.
A tsunami wave is not a tall breaking wave or a tidal wave, although that term is a common misnomer for a tsunami. A tsunami actually resembles a flood or surge, consisting of several waves or surges. The first tsunami surge is often not the highest and the largest surge may occur hours after the first wave. It is not possible to predict how many surges or how much time will elapse between waves for a particular tsunami. This will become a major issue for public safety officials responding to a tsunami.
Visually, tsunamis differ from typical wind waves as well. A tsunami is virtually undetectable to the eye until it has nearly reached the shore. A tsunami looks more like a storm surge experienced in a large hurricane than it does a wind wave. Similar to a hurricane’s storm surge, a tsunami is capable of bringing in large amounts of water inland very quickly, and can inundate areas that are normally dry, even during highest tides. The surges are extremely strong, and the currents uproot and carry everything within its path. These debris filled surges are deadly and destructive to everything in their path.
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In deep ocean water, tsunamis may travel as fast as 600 miles per hour. As they approach the shore, waves may increase in size and can cause extensive damage to coastal structures. 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 walllike 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 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.
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. Waisthigh 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.
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16.1.1 TSUNAMI TYPES
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.
Local Source
Local tsunami sources, like large offshore faults and massive submarine landslides, can put adjacent coastal communities at the greatest risk because the public must respond quickly with little or no official guidance. The time between the earthquake that generates the tsunami and the first wave coming ashore can be as little as 10-20 minutes, certainly not enough time for a full response.
Distant Source
A tsunami caused by an exceptionally large earthquake elsewhere on the Pacific Rim could reach the California coast many hours (4-15) after the earthquake. Scientific equipment from across the globe is able to measure the earthquake, and the amplitude and speed of a resulting tsunami, thus adequate warning and response can be accomplished through proper planning and exercising.
16.2 HAZARD PROFILE
16.2.1 HISTORY
As shown in Table 16-1, ten observed tsunamis generated waves in Monterey County. Almost all of the tsunamis were produced by earthquakes and resulted in wave run-ups of 1 meter or less. In Monterey County, two earthquakes have caused recorded tsunami run-up heights that exceeded 1 meter. The 1960 Chilean Earthquake of estimated magnitude 9.5 (largest ever recorded) caused a 1.1-meter run-up-and killed one person, while the slightly smaller but nearer 1964 Alaska earthquake of magnitude 9.2 caused a 1.4-meter run up and significant boat damage at harbors in the Monterey Bay area.
In 1989, the magnitude 6.9 Loma Prieta earthquake, which was centered inland on the San Andreas fault in the Santa Cruz Mountains, triggered a small to moderate landslide offshore in Monterey Canyon. This caused a 1-foot tsunami measured at the tide gauge in Monterey. In 2011, a tsunami caused by an earthquake off the coast of Japan created large and rapid changes in water level (up to 6 feet) at Moss Landing, causing large volumes of water to rush in and out of the north and south harbor areas. This ebbing and flowing combined with large sediment transport resulted in shear stresses on dock structures in the harbor, causing approximately $1.5 million in damages to 220 timber dock piles.
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Table 16-1: Historic Monterey County Tsunami Events
Table 16-1
Historic Monterey County Tsunami Events
Date Origin Cause
Location of
Effects
Wave
Run-Up Damage
04/01/1946 Aleutian
Islands
Earthquake
(M8.8)
Monterey,
Pacific Grove 3-5 feet Slight turbulence, localized flooding 03/09/1957 Aleutian
Islands
Earthquake
(M8.6) Monterey 2 feet No damage
05/22/1960 Chile Earthquake
(M9.5)
Monterey,
Moss Landing,
Pacific Grove
2-4 feet Severe currents, seawall
submerged, no damage
03/28/1964 Alaska Earthquake
(M9.2)
Monterey,
Moss Landing,
Pacific Grove
5-8 feet
Strong currents, boats
damaged, minor
damage to utilities
10/18/1989 Northern
California
Earthquake
(M6.9)
Monterey,
Moss Landing 1-3 feet No damage
02/27/2010 Chile Earthquake
(M8.8) Monterey 1 foot No damage
03/11/2011 Japan Earthquake
(M9.0)
Monterey,
Moss Landing 2-6 feet
$1.5 million in damages
to dock piles in Moss
Landing Harbor
01/15/2022 Tonga Volcano
Monterey,
Moss Landing,
Pacific Grove
2-3 feet TBD
16.2.2 LOCATION
The entire coastal area of Monterey County is susceptible to a tsunami. The Big Sur coast is less susceptible to significant tsunami run-up due to the rugged and steep cliffs of the coastal mountains. However, the coastal low-lying areas and riverine valleys to the north are highly susceptible to tsunamis.
If a large enough earthquake occurs in the Monterey Bay and produces a tsunami it would reach the shore in a matter of minutes. The San Gregorio Fault, which runs more or less parallel to the coastline, is the likeliest point of origin for a near-shore tsunami event. Although not generally considered a fault capable of producing a “mega-earthquake” (>8.0), it is capable of a large enough earthquake that could trigger an offshore landslide in a submarine canyon in the Monterey Bay. If an event such as this were to occur, any potentially resulting tsunami would reach shore in less than 30 minutes, and possibly as little as 10 minutes.
A tsunami caused by an exceptionally large earthquake elsewhere on the Pacific Rim could reach the California coast many hours (4-15) after the earthquake. A thrust-type earthquake Packet Page 470
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(vertical displacement) is more likely to produce a tsunami than an earthquake from a lateral strike-slip fault, such as the San Andreas. Because of this, subduction zones, where dense oceanic crust burrows underneath less-dense continental crust, are more likely to produce a large tsunami.
Perhaps the most likely source for a significant tsunami exceeding 1 meter in run-up height would be from a rupture along the Cascadia Subduction zone in the Pacific Northwest, which evidence indicates has not had a major rupture since 1700 and could produce an earthquake in the Richter magnitude 9.0 range. The Aleutian Islands and Gulf of Alaska are also capable of producing large offshore earthquakes that may produce large tsunamis.
Since large tsunamis are infrequent and the likelihood that the largest potential tsunamis have not yet occurred in Monterey County, the state tsunami program developed a suite of maximum credible tsunami scenarios as part of their tsunami inundation mapping project for local evacuation planning. The general tsunami wave heights (flow depths) for key locations from these scenarios are provided in Table 16-2, Table 16-3, and Table 16-4. 66 NOTE: The projections do not include any adjustments for ambient conditions, such as storm surge and tidal fluctuations, and model error (it is important to note this difference, as those numbers can increase the projected water height during an event).
Table 16-2: Tsunami Source Scenario Model Results- North County Table 16-2
Tsunami Source Scenario Model Results- North County
Tsunami Source Travel
Time
Location- Near Shore Tsunami Heights
Feet Above Mean Sea Level
Pajaro
River
Moss
Landing
Salinas
River Marina Sand City
Monterey Canyon Landslide 10-15 min 7 5 8 14 7
M9 Cascadia- Full Rupture 1hr 4 3 4
M9.2 Alaska 1964 EQ 5hr 10 7 7 6 10
M8.9 Central Aleutians I 5hr 7 5 7 6 6
M8.9 Central Aleutians II 5hr 4 3 4
M9.2 Central Aleutians III 5hr 12 10 12 12 12
M8.8 Kuril Islands II 9hr 3 3 3
M8.8 Kuril Islands III 9hr 3 3 4
M8.8 Kuril Islands IV 9hr 4 3 3
M8.8 Japan II 10hr 3 3 4
M.8.6 Marianas Trench 11hr 4 2 3 2 3
M9.5 Chile 1960 EQ 13hr 4 3 4
M9.4 Chile North 13hr 7 3 5
Maximum Runup- Local Source 8 6 9 15 8
Maximum Runup- Distant Source 13 11 12 13 13
66 Monterey County Tsunami Playbook
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Table 16-3: Tsunami Source Scenario Model Results- Monterey Table 16-3
Tsunami Source Scenario Model Results- Monterey
Tsunami Source Travel
Time
Location- Near Shore Tsunami Heights
Feet Above Mean Sea Level
Monterey -
Marina
Monterey -
Aquarium
Monterey -
Point Pinos
Monterey Canyon Landslide 10-15 min 7 17 16
M9 Cascadia- Full Rupture 1hr 4 3 3
M9.2 Alaska 1964 EQ 5hr 10 8 7
M8.9 Central Aleutians I 5hr 6 5 4
M8.9 Central Aleutians II 5hr 3 3 3
M9.2 Central Aleutians III 5hr 12 9 7
M8.8 Kuril Islands II 9hr 2 2 2
M8.8 Kuril Islands III 9hr 4 3 3
M8.8 Kuril Islands IV 9hr 3 3 3
M8.8 Japan II 10hr 4 3 3
M.8.6 Marianas Trench 11hr 3 2 2
M9.5 Chile 1960 EQ 13hr 4 3 3
M9.4 Chile North 13hr 5 4 3
Maximum Runup- Local Source 8 18 17
Maximum Runup- Distant Source 13 10 8
Table 16-4: Tsunami Source Scenario Model Results- South County Table 16-4
Tsunami Source Scenario Model Results- South County
Tsunami Source Travel
Time
Location- Near Shore Tsunami Heights
Feet Above Mean Sea Level
Cypress Point Carmel Monastery Beach
Monterey Canyon Landslide 10-15 min 13 4 4
M9 Cascadia- Full Rupture 1hr 3 3 2
M9.2 Alaska 1964 EQ 5hr 7 8 7
M8.9 Central Aleutians I 5hr 5 6 5
M8.9 Central Aleutians II 5hr 3 3 3
M9.2 Central Aleutians III 5hr 9 10 9
M8.8 Kuril Islands II 9hr 2 2 2
M8.8 Kuril Islands III 9hr 3 3 3
M8.8 Kuril Islands IV 9hr 3 3 3
M8.8 Japan II 10hr 3 3 3
M.8.6 Marianas Trench 11hr 2 2 2
M9.5 Chile 1960 EQ 13hr 3 3 3
M9.4 Chile North 13hr 3 3 3
Maximum Runup- Local Source 14 4 4
Maximum Runup- Distant Source 10 12 11
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16.2.3 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 activity or landslides. As noted above, Monterey County has experienced 10 notable tsunamis over the past 100 years and has been impacted significantly by one. Although these numbers could be averaged to generate an expected occurrence rate, there have been as few as 1 and as many as 45 years in between events, and an averaged recurrence interval would not be meaningful. For the purposes of this plan, the probability that Monterey County will experience a tsunami has been estimated to be possible, averaging a 1- foot to 11-foot wave run-up for all coastal and low-lying areas within the county.
16.2.4 SEVERITY
Tsunamis are a threat to life and property to anyone living near the ocean, but the impact of a tsunami can vary widely. The tsunami’s size and speed, as well as the coastal area’s form and depth, affect the impact of a tsunami. A small tsunami may result in unusual tides or currents that can be dangerous to swimmers or cause damage to berthed boats. Powerful tsunamis, such as the one that struck Southeast Asia in December 2004, can level structures, and result in significant loss of human life. Tsunami waves can persist for many hours because of complex interactions with the coast. Large tsunamis cause strong rips and currents in oceans around the world for up to a few days after the initiating earthquake.
When they strike land, most tsunamis are less than 10 feet high, but in extreme cases, they can exceed 100 feet near their source. A tsunami may come onshore like a fast-rising flood or a wall of turbulent water, and a large tsunami can flood low-lying coastal areas more than a mile inland. Rushing water from waves, floods, and rivers is incredibly powerful. Just six inches of fast-moving water can knock adults off their feet, and twelve inches can carry away a small car.
Tsunamis can be particularly destructive because of their speed and volume. They are also dangerous as they return to the sea, carrying debris and people with them. Harbors in particular are vulnerable to damage from strong tsunami currents, potential damage includes:
• Sudden and significant water-level fluctuations can cause boats and docks to hit bottom (grounded) as water levels drop, and docks to overtop piles as water levels rise • Strong and unpredictable currents can occur, especially where there are narrow passages, channels, or harbor openings, or other natural or man-made structures that form constrictions
• Tsunami-induced bores, seiches, and amplified waves can cause swamping of boats and damage to docks
• Eddies/whirlpools can cause boats to break their moorings and float uncontrolled • Drag on deep draught boats can cause damaging forces to the docks they are moored to • Free floating boats, docks, and/or debris in the water can damage structures and infrastructures in the harbor
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• Dangerous tsunami conditions which may potentially last tens of hours after first wave arrival, can cause problems for inexperienced and unprepared boaters who may try to move their boats within harbors, take their boats offshore, or reenter the harbor during a tsunami
• Sediment movement from both erosion and deposition can create hazards to navigation • Environmental issues with debris and contaminants in the water can slow/delay recovery efforts for long periods of time
Overall, the County could see moderate impacts from a tsunami originating in the Pacific Ocean. This could have severe impacts, and the resulting floodwater waves can carry damaging debris and inundate homes, businesses, and government buildings. Figure 16-1 shows the tsunami inundation zones in Monterey County, which demonstrates the extent of potential impacts from a tsunami.
Figure 16-1
Tsunami Hazard Areas in Monterey County
Figure 16-1: Tsunami Hazard Areas in Monterey County
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16.2.5 WARNING TIME
There are two ways to identify if a tsunami may be coming: natural warning and official warning. Strong ground shaking, a loud ocean roar, or the water receding unusually far exposing the sea floor are all nature’s warnings that a tsunami may be coming. If any of these warning signs are observed, the public should immediately go to higher ground. A tsunami may arrive within minutes and may last for eight hours or longer. The public should be instructed to stay away from coastal areas until officials announce that it is safe to return.
Official warnings are issues by the National Tsunami Warning Center (NTWC), which provides information about the tsunami in “bulletins” to the state and local jurisdictions. These bulletins include information about the tsunami source, typically an earthquake (location, depth, magnitude), and forecasts about the impending tsunami itself (alert level, first arrival, maximum amplitudes, or wave height). The National Tsunami Warning Center (NTWC) in Palmer, AK, is the primary warning center for the California coastline and issues four types of tsunami statements, these four levels of “alert” are (from least to greatest significance):
• Tsunami Information Statement: Issued to inform and update emergency managers and the public that an earthquake has occurred, or that a tsunami Watch, Advisory or Warning has been issued elsewhere in the ocean.
• Tsunami Watch: Issued to alert emergency managers and the public of an event which may later impact the Watch area. May be upgraded to an Advisory or Warning - or canceled - based on updated information and analysis.
• Tsunami Advisory: Issued due to the threat of a tsunami which may produce strong currents or waves dangerous to those in or near the water; typically called when forecasted tsunami amplitudes between 0.3m and 1m (1ft and 3ft) above existing tidal conditions are expected. Coastal communities are advised that beach and harbor areas could expect rapid, moderate tidal changes and strong currents. • Tsunami Warning: Issued when a tsunami with significant widespread inundation is imminent or expected; typically called when forecasted tsunami amplitudes are equal to or greater than 1m (3ft). Coastal communities are advised to evacuate people from lowlying areas identified as vulnerable to tsunamis.
It is important to note that Tsunami Advisories and Warnings are situations where coastal emergency managers and harbor masters are recommended to take action to protect lives and property, including limiting access to beaches or waterfront areas to full evacuation of the local official evacuation zone identified in their emergency response plans. While the potential for disaster exists with a Tsunami Watch, the situation is truly unknown at the time a watch is issued. The public is only asked to monitor the situation in case an advisory or warning may be issued at a later time.
The following actions and impacts are recommended based on the type of tsunami alert that is issued:
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This official alert system is not considered to be effective for communities close to the tsunami source, because the first wave would arrive before the data can be processed and analyzed, and communications systems may be impacted by the precipitating event. In this case, strong ground shaking would provide the first warning of a potential tsunami and evacuations should begin immediately.
16.3 SECONDARY HAZARDS
A tsunami is always a secondary hazard because it requires an earthquake or landslide to displace a vast volume of water. Secondary hazards can trigger tertiary hazards, for example in 2011 Japan experienced a triple disaster, a subduction zone earthquake with a magnitude of
9.0 that triggered the devastating tsunami which in turn caused a cooling system failure at the Fukushima Nuclear plant.
Additionally, evacuation routes could be blocked as a result of the source of the tsunami such as landslides, power lines, or other debris. People could be trapped in damaged buildings along the waterfront and not be able to evacuate before a tsunami arrives.
16.4 RISK ASSESSMENT
16.4.1 POPULATION
In Monterey County, as seen, in Table 16-5, close to 8,000 people are exposed to tsunami inundation areas.
Table 16-5: Population in Tsunami Inundation Zone
Table 16-5
Population in Tsunami Inundation Zone
Supervisorial District Population
District 1 0
District 2 3,725
District 3 0
District 4 122
District 5 3,740
Total 7,587
Warning Inundating wave possible Full evacuation suggested Advisory Strong currents likely Stay away from the shore Watch Danger levels not yet
known
Stay alert for more
information
Information Minor waves at most No action suggested
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16.4.2 PROPERTY
As seen in Table 16-6, in Monterey County, about 850 residential properties, close to $2 billion in residential property value, is located in tsunami inundation areas.
Table 16-6: Residential Property in Tsunami Inundation Zone Table 16-6
Residential Property in Tsunami Inundation Zone
Supervisorial District Number of Properties Property Value District 1 0 $0
District 2 232 $151,714,929
District 3 0 $0
District 4 3 $735,480
District 5 610 $1,784,859,471
Total 845 1,937,309,880
Summarized in Table 16-7, about 3,500 non-residential properties, close to $1.5 billion in value is located in tsunami inundation areas.
Table 16-7: Non-Residential Property in Tsunami Inundation Zone Table 16-7
Non-Residential Property in Tsunami Inundation Zone
Supervisorial District Number of Properties Property Value District 1 0 $0
District 2 1,661 $255,042,798
District 3 0 $0
District 4 183 $219,994,034
District 5 1,718 $1,050,596,597
Total 3,562 $1,525,633,429
16.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
Roads are the primary resource for evacuation to higher ground before and during a tsunami event. Roads also can serve as flood control facilities for low depth, low velocity floods by acting as levees or berms and diverting or containing flood flows. The major road in the County that intersect tsunami inundation areas is Highway 1. This is a major road that may be impacted by a tsunami, based on exposure; it is NOT an evacuation route for tsunami events. Evacuation routes are identified in emergency response plans in effect within the County. Bridges exposed to tsunami events can be extremely vulnerable to forces transmitted by wave run-up and by debris carried by the wave action. Additionally, a tsunami would impact and damage the infrastructure and equipment in the Monterey and Moss Landing Harbors.
Water and sewer systems can be affected by the flooding associated with tsunami events.
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 Packet Page 477
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drinking water supplies, causing contamination. Sewer systems can be backed up, causing waste to spill into homes, neighborhoods, rivers, and streams. Tsunami waves can knock down power lines and radio/cellular communication towers. Power generation facilities can be severely impacted by wave action and by inundation from floodwater.
Table 16-8 summarizes critical infrastructure in the mapped tsunami inundation zone in Monterey County.
Table 16-8: Critical Infrastructure in Tsunami Inundation Zone in Monterey County Table 16-8
Critical Infrastructure in Tsunami Inundation Zone in Monterey County Critical Infrastructure Type Tsunami Inundation Zone
Facilities
Emergency Response 0
Fire Station 0
Police Station 0
Medical Facilities 0
Military Facility 0
Large Public Facilities 0
Educational Facilities 2
Power Plant 0
Water & Wastewater Facilities 10
Stormwater Facilities 1
Government Facilities 0
Communication Facilities 7
Rain Gauges 2
Lighthouses 0
Dams 0
Hazardous Materials
Active or Idle Oil Well 3
Landfill 0
Underground Tank 0
Cal ARP Facility 0
Transportation
Airport 0
Bridge 7
Harbor 2
Highway/Freeway (Miles) 0
Driveway (Miles) 0
Major Road (Miles) 9
Local (Miles) 10
Railroad (Miles) 4
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16.4.4 ENVIRONMENT
Inundation of water by tsunami and introduction of foreign debris could be hazardous to the environment. All wildlife inhabiting the inundation area is exposed. The vulnerability of aquatic habit and associated ecosystems would be highest in low-lying areas of the Monterey Bay coastline and the protected wetland habitats in the Elkhorn and Moro Cojo Slough. Tsunami waves can carry destructive debris and pollutants that can devastate the environment. Millions of dollars spent on habitat restoration and conservation in Monterey County could be wiped out by one significant tsunami. There are currently no tools available to measure these impacts.
However, the potential financial impact of a tsunami event on the environment could equal or exceed the impact on property. Community planners and emergency managers should take this into account when preparing for the tsunami hazard and considering future development.
16.4.5 ECONOMIC IMPACT
A tsunami along the coast of Monterey could have an impact on the tourism industry, which is the second largest industry in the County. A tsunami could also impact coastal dependent industries such as harbors, marine sciences, and commercial fishing, as well as effect agricultural operations near the coast.
16.5 FUTURE TRENDS IN DEVELOPMENT
Future development is possible in tsunami inundation zones, but it is likely to be limited due to already regulated flood risk in the areas at risk to tsunami inundation.
16.6 ISSUES
Important issues associated with a tsunami in the County include the following:
• As tsunami warning technologies evolve, the tsunami warning capability within Monterey County 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 tsunami inundation areas are identified through future studies.
• Lack of understanding of inundation areas has resulted in over self-evacuation; in past incidents people have self-evacuated to the City of Salinas. Further public information and socialization of tsunami risks may be required.
• Special attention will need to be focused on the vulnerable communities in the tsunami zone and on hazard mitigation through public education and outreach.
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17. UTILITY INTERRUPTION
17.1 OVERVIEW
Utility interruptions are electrical, natural gas, sewage, telecommunication, or water failures or interruptions that affect people.
Power Failure
A power failure is any interruption or loss of electrical service due to disruption of power generation or transmission caused by an accident, sabotage, natural hazards, equipment failure, or fuel shortage. These interruptions can last anywhere from a few seconds to several days. Power failures are considered significant only if the local emergency management organization is required to coordinate basic services such as the provision of food, water, and heating as a result. Power failures are common with severe weather and winter storm activity.
Pacific Gas and Electric (PG&E) is responsible for operating and maintaining the electrical transmission and distribution system in the County.
The scope and scale of electrical power disruption impacts will vary based on how widespread the disruption is, when and where it occurs, its duration, its cause, the characteristics of the affected population and region, and other concurrent emergencies. While the electric power industry does not have a universal agreement for classifying disruptions, it is important to recognize that different types of outages are possible, so that plans may be made to handle them effectively. Electric power disruptions can generally be grouped into two categories:
• Intentional Electrical Disruptions: Some disruptions are purposefully done to upgrade, fix, or protect electrical power systems and/or the surrounding area. Intentional power Packet Page 481
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disruptions can be scheduled or done without notice and can last several minutes to several days; when possible, the electrical service provider will give the Operational Area and its customers advance notice of the disruption. • Unintentional Electrical Disruptions: Unintentional disruptions are not done purposefully, range in duration and often occur without notice. These types of disruptions include:
o Accidents by the utility provider, contractor, or others o Malfunctions or equipment failures, due, for example, to age, improper operation, excessive operation, or manufacturing defect o Overloads on either the utility's equipment or a customer's equipment o Equipment that cannot operate within its design criteria (known as reduced capability)
o Tree contact
o Vandalism or intentional damage
o Disasters, such as extreme weather/winds, earthquakes, floods, and wildfires Load Shedding: Load Shedding occurs when the power system is under extreme stress, due to heavy demand and/or failure of critical components, the electrical service provider may interrupt or cut service (or load) to select customers to prevent the entire system from collapsing. This can be done with or without warning.
Public Safety Power Shutoff (PSPS): The State's investor-owned electric utilities, including Pacific Gas and Electric Company (PG&E), may shut off electric power, referred to as "deenergization" or Public Safety Power Shut-offs (PSPS), to protect public safety under California law, specifically California Public Utilities Code (PU Code) Sections 451 and 399.2(a). This is done to reduce the chance of fire ignition in high fire threat areas. PG&E has stated they may de-energize, or shutoff power, to electrical grids or blocks of areas in advance of or during periods of heightened risk of wildland fires. In these instances, power will remain out for as long as extreme and dangerous conditions pose a potential fire risk and until PG&E can inspect and repair power lines and equipment. Once the electrical service provider deems it is safe to do so, power will be systematically restored.
Water or Wastewater Disruption
Water or wastewater disruption is a secondary impact from a natural disaster or intentional act.
A breach in the pipelines that carry water through the County would have significant temporary impacts until alternative water sources are pumped and treated. Long-term disruption would have significant impacts on residences and businesses in the planning area if demand exceeds secondary supplies and water conservation measures do not provide enough relief to reduce demand to equal the secondary supplies.
Disruption of the County’s wastewater collection and wastewater treatment plants would have significant regional impacts. Such disruption could result if the system were to be overwhelmed by a significant storm or discharge of materials in such quantities that the treatment plant could not adequately treat the waste. Natural hazards such as earthquake or flood, major power Packet Page 482
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outages, or terrorism directed at the facilities and systems could disrupt the process of collecting and treating millions of gallons of sewage. Wastewater treatment plants may also have emergencies internal to the plant such as oxygen deficiencies that render them incapable of treating waste. The disruption of service may also have significant environmental impacts on the waterways adjacent to the treatment plants.
Data and Telecommunications Interruptions
The loss of data or telecommunications is often a secondary hazard to natural and other human-caused hazards. Data and telecommunications provide a primary method for service to the community by the government and the private sector. A loss of data and telecommunications could result in loss of emergency dispatch capabilities, emergency planning services, infrastructure monitoring capabilities, access to statistical data, and access to financial and personnel records.
Pipeline Interruptions
Pipelines are often considered the safest and most reliable way to transport natural gas, crude oil, liquid petroleum products, and chemical products, but there is still an inherent risk due to the nature of the hazardous materials. Failures of pipelines can occur when pipes corrode, are damaged during excavation, are incorrectly operated, or are damaged by other forces.
Intra-state liquid petroleum pipelines are regulated by the Office of the State Fire Marshal Pipeline Safety Division. Natural gas pipelines are regulated by the California Public Utilities Commission. Pipelines are also monitored by supervisory control and data acquisition systems that measure flow rate, temperature, and pressure. These systems transfer real-time data via satellite from the pipelines to a control center where valves, pumps, and motors are remotely operated. If tampering with the pipeline occurs, an alarm will sound. The ensuing valve reaction is instantaneous, with the system isolating any rupture and setting off a chain reaction that shuts down pipeline pumps and alerts pipeline operators within seconds.
Transmission pipelines and distribution pipelines provide different services. Transmission pipelines transport raw material for further refinement. These pipes are large and far reaching, operating under high pressure. Distribution pipelines provide processed materials to end users.
These are smaller in diameter, some as small as a half an inch, and operate under lower pressure. More serious accidents occur on distribution pipelines than on any other type due to their number, intricate networking, and location in highly populated areas.
17.1.1 SPACE WEATHER
All weather on Earth, from the surface of the planet 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 on Earth. Extreme space weather can cause damage to critical infrastructure, especially the electric grid. It can produce electromagnetic fields that induce Packet Page 483
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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 ranging from minor to extreme effects as a way to communicate to the general public the current and future space weather conditions and their possible effects on people and systems. Descriptions of three general NOAA classifications of space weather— geomagnetic storms, solar radiation storms and radio blackouts—are included in Figure 17-1. NOAA Space Weather Prediction Center 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% over the course of the 11-year solar cycle.
• At ultraviolet or UV wavelengths, solar irradiance is more variable, with changes up to 15% over the course of the 11-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% 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 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.
Space weather (geomagnetic storms, solar radiation storms, solar flare radio blackouts, solar radio bursts, and cosmic radiation) can impact aviation operations at the Monterey Airport.
Effects include degradation or loss of HF radio transmission and satellite navigation signals; navigation system disruptions; and avionics errors. Airport dispatchers use space weather forecasts for flight planning at high latitudes, especially for polar routes.
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Figure 17-1
Figure 17-1: NOAA Space Weather Scales
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17.2 HAZARD PROFILE
17.2.1 HISTORY
The Monterey County Emergency Operations Center (EOC) was activated for a PSPS in 2019. On October 26-29, 2019, Pacific Gas and Electric Company de-energized areas of incorporated and unincorporated Monterey County resulting in prolonged complete loss of electricity due to a Public Safety Power Shutoff (PSPS). Those impacted included:
• Customers De-Energized: 10,607 Total Customers
• 279 Medical Baseline Customers
• 79 Critical Facilities, including the Salinas Valley State Prison During 2021, multiple utility interruptions occurred. The January 2021 atmospheric river event caused both telecommunications and power outages in the County. On August 5, 2021, the explosion of multiple transformers in the City of Soledad caused at one point in time, the loss of power to over 3,500 customers. On the same day, a car crash into a power pole caused outages in the City of Greenfield.
On August 15, 2021, over 2,500 customers in the Carmel Valley lost power due to unknown causes. From October 9-10, 2021, Pacific Gas and Electric Company de-energized areas of incorporated and unincorporated Monterey County resulting in prolonged complete loss of electricity due to a Public Safety Power Shutoff (PSPS). Around 850 customers lost power for some amount of time.
There have also been a number of telecommunications outages that have impacted County residents. In November of 2021, AT&T had a major fiber cut between Salinas and Gonzales, Packet Page 486
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which affected every AT&T provided service in South County, including the transport from cell sites to AT&T's backbone. AT&T's Big Sur cellular service was also affected since it connects at Greenfield.
17.2.2 LOCATION
Electrical generation, transmission, and distribution system are located throughout the County.
Previous significant Public Safety Power Shutoff events have impacted Unincorporated Monterey County: Aromas, Gabilan Foothills, Carmel Valley, Chualar; and Incorporated Cities of Monterey County: City of Gonzales, City of Soledad, City of Greenfield.
Space Weather
Different types of space weather can affect different technologies in the County. Solar flares can produce strong x-rays that degrade or block high-frequency radio waves used for radio communication during events known as radio blackout storms. Solar energetic particles can penetrate satellite electronics and cause electrical failure. These energetic particles also block radio communications at high latitudes during solar radiation storms. Coronal mass ejections can cause geomagnetic storms on Earth and induce extra currents in the ground that can degrade power grid operations and modify the signal from radio navigation systems (GPS), causing accuracy to be degraded.
17.2.3 FREQUENCY
The frequency of utility failure and power interruption is likely to remain constant, but the length of time a utility is shut down should lessen in the future as more redundancies are built into infrastructure and utilities. In addition, leak detection sensors alert utilities to faults and failures more quickly.
Space Weather
Space weather events occur daily, but do not always affect residents in the County. They are all monitored and reported by NOAA’s Space Weather Prediction Center.
17.2.4 SEVERITY
The severity of utility failure and power interruptions varies too widely to be able to measure.
Electricity, for example, may be out for a few hours to several weeks, depending on the cause of the event.
Space Weather
The severity of space weather can be far-reaching, as virtually all infrastructure and services depend on the electric power grid. Ground currents induced during geomagnetic storms can melt copper windings of transformers, which are the primary components of power distribution systems. Power lines traversing the County can pick up the currents and spread the problem over the entire area.
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17.2.5 WARNING TIME
Utility failure and power interruptions occur at any time without warning. However, they usually are a secondary effect from a storm event, landslide, or human-caused issues.
Space Weather
Space weather prediction services in the United States are provided primarily by NOAA’s Space Weather Prediction Center and the US Air Force’s Weather Agency, which work closely together to address the needs of 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.
17.3 SECONDARY HAZARDS
Utility losses can cause a reduction in employment and in wholesale and retail sales, require utility repairs, and increase medical risk. Local government may lose tax revenue, and the finances of private utility companies and the businesses that rely on them can be disrupted.
Space Weather
The most likely secondary impact of space weather on residents, businesses and visitors to the County is disruption of the electric power grid. Space weather can have an impact on advanced technologies, which has a direct impact on daily life.
17.4 RISK ASSESSMENT
17.4.1 POPULATION
All residents and visitors in the County are exposed to utility interruptions. This will continue as people are dependent on basic utility services such as electricity, water, wastewater, natural gas, etc. Utility disruptions can have both a direct impact on society and trigger or worsen disruptions to water, transportation, and other systems, that in turn may cause further societal impacts. Additional emergencies occurring during power disruptions can compound these effects and influence the timeline of restoration. Depending on the circumstances surrounding the incident, utility disruption can impact transportation/fuel, communications, housing, critical infrastructure, first response, and the economy.
Space Weather
Space weather exposure of the County’s population is minimal. The main exposure is of satellite operations, HF radio communications, and the power grid that people use.
17.4.2 PROPERTY
All property throughout the County is exposed to some type of utility infrastructure failure.
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Space Weather
It is unlikely that the impacts of space weather would have a negative impact on property and structures themselves, but a magnetic or black-out event caused by space weather, would affect public and private infrastructure systems.
17.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
All critical facilities and infrastructure that are operated by electricity are exposed to utility interruption and a space weather phenomenon. Damage to critical facilities can disrupt health care, fire and police services and impair search and rescue and emergency medical care.
17.4.4 ENVIRONMENT
The environment is usually not exposed to utility interruption unless it is a spill that contaminates water or open land or creates a wildfire that burns acres.
Space Weather
Migratory animals are exposed to geomagnetic storms associated with space weather.
17.4.5 ECONOMIC IMPACT
Utility losses could cause a reduction in employment and wholesale and retail sales, a need for utility repairs, and increased medical risks. Local governments might lose tax revenues, and the finances of private utility companies and the businesses that rely on them would be disrupted.
Utility interruption can also affect agricultural production, which can have a large economic effect on Monterey County.
FEMA has developed standard loss-of-use estimates in conjunction with its benefit-cost analysis methodologies to estimate the cost of lost utilities on a per-person, per-use basis, as summarized in Table 17-1.
Table 17-1: FEMA Standard Values for Loss of Services for Utilities and Roads/Bridges Table 17-1
FEMA Standard Value for Loss of Service for Utilities and Roads/Bridges Interruption Total Economic Impact
Complete Loss of Electric Power $126 per person per day Complete Loss of Potable Water Service $93 per person per day Complete Loss of Wastewater Service $41 per person per day Complete Loss of Road/Bridge Service $38.15 per vehicle per hour of vehicle delay; $0.55 per mile of vehicle delay (current mileage rate)
Source: FEMA BCA Reference Guide, June 2009, Appendix C FEMA Standard Values Packet Page 489
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17.5 FUTURE TRENDS IN DEVELOPMENT
The likelihood of utility interruption in the future will continue as development and population growth continue in the County. The majority of utilities in the County are privately owned, and market forces are, as a rule, insufficient to induce needed investments in protection. Private organizational strategies and policies will need to work together to ensure reliable and resilient services for the long term.
17.6 ISSUES
Key issues associated with utility interruptions in Monterey County include:
• Heat-related equipment failures and electrical infrastructure igniting wildfires has resulted in unintentional and intentional rolling blackouts and power shutoffs throughout the County. Public Safety/ Utility Initiated Power Shut Offs to prevent wildfire ignition can have notably significant impacts due to the length of disruption time, limited efficacy of the strategy, and the effect on first responder capabilities. • The economic impact of utility interruptions on industry, particularly the agricultural industry is a large concern in the County. Loss of power for more than a few hours can result in large economic losses.
• More vulnerable populations in isolated areas or who rely on medical devices are at increased risk during prolonged power outages.
• Extreme and prolonged heatwaves across the state increase the demand for use of the aging electrical grid significantly depleting electricity reserves resulting in blackouts.
Heatwaves are expected to increase in intensity and magnitude due to climate change, which will likely exacerbate this problem.
• Monterey County has limited microgrids and reliance on the macro-grid makes the County vulnerable to rolling and prolonged power outages.
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18. WILDFIRE
18.1 OVERVIEW
A wildfire is any uncontrolled fire occurring on undeveloped land that requires fire suppression.
Wildfires can be caused by human activities (such as arson or campfires) or by natural events such as lightning. Wildfires are costly, putting lives and property at risk and compromising rivers and watersheds, open space, timber, range, recreational opportunities, wildlife habitats, historic and cultural areas assets, scenic assets, and local economies. Vulnerability to flooding increases due to the destruction of forest and ground cover within watersheds. The potential for significant damage to life and property increases in areas where development is adjacent to dense vegetation, known as wildland urban interface (WUI) areas.
Reported outcomes of wildfire typically include only those that are attributable to the physical fire itself; these outcomes largely occur during the fire event and within or near the wildfire perimeter. However, wildfires can also generate smoke plumes or increase the risk of postwildfire landscape events such as erosion, debris flows, and flooding.
18.1.1 WILDFIRE PROTECTION RESPONSIBILITY AREAS
Local, state, tribal, and federal organizations all have legal and financial responsibility for wildfire protection. In many instances, two fire organizations have dual primary responsibility on the same parcel of land—one for wildfire protection and the other for structural fire protection. To address wildfire jurisdictional responsibilities, the California State Legislature outlined various wildfire responsibilities, described below, in Cal. Pub. Res.Code§4291.5 and Cal. Health & SafetyCode§13108.5. Figure 18-1 shows the Fire Protection Responsibility areas Packet Page 491
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(Federal Responsibility Areas, State Responsibility Areas, and Local Responsibility Areas) in Monterey County.
Federal Responsibility Area (FRA)
Federal Responsibility Areas (FRA) are fire-prone wildland areas that are owned or managed by a federal agency. Primary financial and rule-making jurisdictional authority rests with the federal land agency. In many instances, FRAs are interspersed with private land ownership or leases. Fire protection for developed private property is usually not the responsibility of the federal land management agency; structural protection responsibility is that of a local government agency.
The agencies that control federal lands within Monterey County include:
• US Forest Service: Los Padres National Forest
• National Park Service: Pinnacles National Park
• Dept. of Defense: Fort Hunter Liggett, Defense Language Institute, Presidio of Monterey • Bureau of Land Management: Various
• California National Guard: Camp Roberts
State Responsibility Area (SRA)
State Responsibility Areas (SRA) are lands in California where California Department of Forestry and Fire (CAL FIRE) has legal and financial responsibility for wildfire protection and administers fire hazard classifications and building standard regulations. SRAs include forested lands and land that is generally considered wildland. SRAs do not include incorporated cities or federal lands. CAL FIRE is responsible for carrying out the mandate for wildland fire protection within SRAs. The CAL FIRE San Benito-Monterey Unit (BEU) provides wildland fire protection to the 2.1 million acres of SRA land in the County.
The law also allows CAL FIRE to provide fire protection services to local communities under contract. When contracting to provide services, authority is delegated to CAL FIRE by the contracting agency. CAL FIRE will respond to reported fires and may provide EMS and other incident responses as contracted for. SRAs may overlap some or all of a special district’s jurisdiction, as is the case in unincorporated Monterey County.
CAL FIRE BEU has Cooperative Fire Protection Agreements with the Pebble Beach Community Services District, the Cypress Fire Protection District, the Carmel Highlands Fire Protection District, the Aromas Tri-County Fire Protection District, the South Monterey County Fire Protection District, and the Soledad Fire Department. They have Dispatch Agreements with the Cachagua Fire Protection District and the Mid Coast Volunteer Fire Brigade.
Local Responsibility Area (LRA)
Local Responsibility Areas (LRAs) include land in cities, cultivated agriculture lands, nonflammable areas in unincorporated areas, and lands that do not meet the criteria for SRA or FRA. LRA fire protection is typically provided by city fire departments, fire protection districts, Packet Page 492
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and counties, or by CAL FIRE under contract to local governments. LRAs may include flammable vegetation and wildland urban interface areas where the financial and jurisdictional responsibility for improvement and wildfire protection is that of a local government agency.
Figure 18-1
Fire Protection Responsibility Areas in Monterey County Figure 18-1: Fire Protection Responsibility Areas in Monterey County
18.1.2 FIRE PROTECTION DISTIRCTS AND AGENCIES
The special districts providing fire protection services cover about 1,497 square miles, almost half of the 3,281 square miles of land area in Monterey County.
Table 18-1 summarizes the Fire Protection Districts and service areas of the Fire Protection Districts are mapped in Figure 18-2.
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Table 18-1: Fire Protection Districts in Monterey County Table 18-1
Fire Protection Districts in Monterey County
Fire Protection District
Estimated
Area (Square
Miles)
Estimated
Population
Responding
Agency
ISO Public
Protection
Classification
Aromas Tri-County Fire
Protection District 17.3 5,800 CAL FIRE BEU 4 / 4X
Big Sur Volunteer Fire
Brigade 254.0 4,350 Big Sur Fire 8 / 10
Cachagua Fire Protection
District 108.0 1,000 Cachagua Fire 9 / 10
Carmel Highlands Fire
Protection District 9.3 1,075 CAL FIRE BEU 2 / 9
Cypress Fire Protection
District 11.4 7,600 CAL FIRE BEU 2 / 9
Gonzales Rural Fire
Protection District 58.4 650 Gonzales Fire 3 / 3X (5 in City) Greenfield Fire Protection
District 43.2 700 Greenfield Fire 5 / 10
Mid-Coast Volunteer Fire
Brigade 41.0 270 Mid-Coast Fire 5 / 7B
Mission Soledad Rural Fire
Protection District 59.6 1,150 CAL FIRE BEU 3 / 10 (4 in City) Monterey County Regional
Fire Protection District 399.6 38,350 Regional Fire 3 / 10 North County Fire
Protection District 122.9 42,000 North County Fire 4 /10 Pebble Beach Community
Services District 8.3 4,100 CAL FIRE BEU 1
South Monterey County
Fire Protection District 637.2 4,600 CAL FIRE BEU 8 / 10 Aromas Tri-County Fire Protection District
The Aromas Tri-County Fire Protection District provides fire protection and emergency medical services to approximately 5,800 people throughout forty square miles in the northeast corner of Monterey County and adjacent areas of San Benito and Santa Cruz Counties. Monterey County is the district’s principal county because it has the highest assessed value among the three counties within the district’s boundaries. The district provides services through a contract with CAL FIRE.
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Big Sur Volunteer Fire Brigade
The Big Sur Volunteer Fire Brigade provides services to the rural community of Big Sur. The Brigade is a 501(c)3 nonprofit and is not a public agency. The Brigade provides fire protection and emergency medical services to approximately 4,350 people over an area of 254 square miles along the southern half of Monterey County coastline and to the inland to areas within the Los Padres National Forest. The Brigade is staffed by volunteers.
Cachagua Fire Protection District
The Cachagua Fire Protection District provides fire suppression and emergency medical services to the rural and mountainous areas at the eastern end of Carmel Valley, known as the Cachagua area. The district comprises approximately 108 square miles of territory and serves over 1,000 residents. The Fire Protection District is staffed by volunteers.
Carmel Highlands Fire Protection District
The Carmel Highlands Fire Protection District provides services through a contract with CAL FIRE. The district provides a high level of fire protection and emergency paramedic medical services to approximately 1,075 people throughout 9 square miles in the coastal area south of Carmel-by-the-Sea. The district works closely with two adjacent districts - the Cypress Fire Protection District and the Pebble Beach Community Services District - that are both also serviced by CAL FIRE. These three special districts operate what is essentially a seamless regional fire department. The residents of these three special districts benefit from a sharing of stations, apparatus, and staffing. The arrangement has been formed through cost sharing agreements, without the formality or bureaucracy of consolidation.
Cypress Fire Protection District
The Cypress Fire Protection District provides services through a contract with CAL FIRE. The district provides a high level of fire protection and emergency paramedic medical services to approximately 7,600 people throughout 11 square miles within the mouth of the Carmel Valley, and unincorporated portions of Carmel and Monterey. As mentioned above, the district works closely with the Carmel Highlands FPD and the Pebble Beach Community Services District, which are also staffed through CAL FIRE.
Gonzales Rural Fire Protection District
The Gonzales Rural Fire Protection District provides fire protection and emergency medical services to approximately 650 people throughout 58 square miles in the rural area surrounding the City of Gonzales. The small size of the district does not allow it to economically maintain independent fire protection service, so the district has contracted with the City of Gonzales to provide fire protection and emergency medical services within District boundaries.
Greenfield Fire Protection District
The Greenfield Fire Protection District provides fire protection and emergency medical services to approximately 700 people throughout 43 square miles in the rural area surrounding the City Packet Page 495
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of Greenfield. The district contracts with the City of Greenfield to receive fire protection and emergency medical services from the City Fire Department.
Mid-Coast Volunteer Fire Brigade
The Mid-Coast Volunteer Fire Brigade provides services to the rural communities of Garrapata, Palo Colorado, Rocky Creek, Bixby, and the coast from Garrapata State Park south to “South Forty” on Hurricane Point. The Brigade is a 501(c)3 nonprofit and is not a public agency. The Brigade provides fire protection and emergency medical services to approximately 270 people over an area of 41 square miles along the middle of Monterey County’s coastline and to the inland rural areas. The Brigade is staffed by volunteers.
Mission Soledad Rural Fire Protection District
The Mission Soledad Rural Fire Protection District provides fire protection and emergency medical services to approximately 1,150 people throughout 60 square miles in the rural area surrounding the City of Soledad. The district has provided services through a contract with the City of Soledad. The City of Soledad, in turn, contracts with CAL FIRE to provide services to the City and District.
Monterey County Regional Fire District
Monterey County Regional Fire District provides services from rural areas north of the City of Salinas south to the Federal Ventana Wilderness and the outskirts of the City of Gonzales, from the Cities of Marina, Seaside, and Monterey on the west to the San Benito County line in the east. The district provides a high level of fire protection and emergency paramedic medical services to approximately 38,350 people throughout its 400-square mile district. The district also provides ambulance service to Carmel Valley residents.
North County Fire Protection District of Monterey County North County Fire Protection District of Monterey County provides services to rural communities in northern Monterey County. The district provides fire protection and emergency medical services to approximately 42,000 people throughout 123 square miles.
Pebble Beach Community Services District
The Pebble Beach Community Services District provides a high level of fire protection and emergency paramedic medical services to approximately 4,100 people throughout 8 square miles to the north of the City of Carmel and to the west of Cities of Monterey and Pacific Grove.
The district provides services through a contract with CAL FIRE. As noted previously, the district works closely with the Carmel Highlands and Cypress Fire Protection Districts, which are also staffed through CAL FIRE.
South Monterey County Fire Protection District
The South Monterey County Fire Protection District provides fire protection and emergency medical services to a large unincorporated portion of the southern Salinas Valley, including Arroyo Seco, the San Antonio Valley, and the unincorporated area around King City. The district provides services to approximately 4,600 people throughout its 637-square mile district. South Packet Page 496
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Monterey County FPD serves the largest geographic area of any of the County’s fire protection districts. The district provides services through a contract with CAL FIRE.
Figure 18-2
Fire Protection Districts in Monterey County
Figure 18-2: Fire Protection Districts in Monterey County
18.1.3 THE FIRE EQUATION
The following three factors contribute significantly to wildland fire behavior and can be used to identify wildland fire hazard areas.
• Topography: As slope increases, the rate of fire spread increases. South-facing slopes are subject to more solar radiation, making them drier, which intensifies fire behavior. • Fuel: The type and condition of vegetation plays a significant role in the occurrence and spread of wildland fires. Certain types of plants are more susceptible to burning or will burn with greater intensity. Dense or overgrown vegetation increases the amount of combustible material available to fuel the fire. The ratio of living to dead plant matter and the fuel’s continuity, both horizontally and vertically are also important factors. The Packet Page 497
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risk of fire is increased significantly during periods of prolonged drought as the moisture content of both living and dead plant matter decreases. • Weather: The most variable factor affecting fire behavior is weather. Temperature, humidity, wind, and lightning can affect ignition and spread. High temperatures and low humidity can lead to extreme wildfire activity. By contrast, cooling and higher humidity often signal reduced wildfire occurrence and easier containment.
Vegetation Management and Fuel Reduction
Since fuel reduction is the one element of
the fire equation that can be impacted,
vegetation management and clearance
around structures is key to reducing risk. A
number of agencies in the County are
involved in various fuel reduction activities. A
variety of strategies and projects have been
deployed in an effort to reduce the threat of
wildfires.
CAL FIRE BEU administers a Vegetation
Management Program. The purpose of the
program is to reintroduce fire to the
landscape, restoring aspects of historic fire
regimes, and to reduce flammable
vegetation that may contribute to large,
damaging wildfires and high fire suppression
costs. The Vegetation Management Program
is a cost-sharing program that focuses on the
use of prescribed fire and mechanical means
for addressing wildland fire fuel hazards and
other resource management issues on State
Responsibility Area (SRA) lands. The program
allows private landowners to enter into a
contract with CAL FIRE to use prescribed fire
to accomplish a combination of fire
protection and resource management goals.
CAL FIRE also manages some significant
shaded fuel break projects at strategic, highrisk locations.
Local fire agencies conduct property
inspections for defensible space, implement
community projects, and share public
Mitigation Success Story
Monterey Fire Defensible Space Inspection
In order to mitigate the threat of wildfires, the
City of Monterey Fire Department conducts
annual Defensible Space Inspections of all
residential parcels in its response area, which
includes the cities of Monterey, Pacific Grove,
Carmel-by-the-Sea, and Sand City, as well as
the Monterey Regional Airport. Tracking the
inspection status of each parcel was a
challenge.
In 2020, Monterey Fire collaborated with the
City to develop a collector app using GIS
technology. The app allows fire crews to
conduct inspections and record if a parcel is
compliant with defensible space requirements.
The results of the inspection are immediately
visible online in a public facing portal. As
follow-up inspections are completed, the
information can be quickly updated. Staff can
immediately see which parcels need follow-up
and the completion rate. A project that used
to take several months and often resulted in
some missed parcels, can now be completed in
a few weeks with a higher success rate.
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information on wildfire risk. Monterey County Public Works conducts roadside clearance operations with priority given to roadways considered to be primary evacuation routes.
Other agencies and organizations also take a role in vegetation management and fuel reduction. The Fire Safe Council of Monterey County is a non-profit organization committed to protecting lives and property from harm by wildfires, and to educating the public on wildfire dangers and how to reduce them. The Council coordinates projects and is a conduit for fuel reduction grants. They also coordinated the publication of the Monterey County Community Wildfire Protection Plan.
The Resource Conservation District of Monterey County (RCDMC) administers a Fire and Fuels Mitigation Program. Through the program the RCDMC has assisted with grant funding and coordination for fuels projects, fire infrastructure and natural resources mapping, prescribed burning, and wildfire prevention outreach in Monterey County. The program also has been instrumental in assisting other local groups with work that includes promoting prescribed burning, mapping, and defensible space. Key projects include:
• Los Padres Strategic Community Fuel Break Collaborative Project • Prescribed burn association for Monterey, San Benito, and Santa Cruz counties
18.1.4 DEVELOPMENT PATTERNS AND WILDFIRE HAZARD
It is important to differentiate wildland fires from fires that occur in the wildland urban interface (WUI). The WUI refers to the area where houses intermingle with undeveloped wildland vegetation. The potential for significant damage to life and property exists in the WUI where development is adjacent to vegetated areas. The impacts and strategies for prevention and mitigation differ significantly between wildland fires and fires in the WUI. For example, fuel loads for wildland fires consist primarily of vegetation, whereas WUI fires have fuel loads consisting of vegetation and houses.
WUI fires have become a defining challenge for California as development continues to expand into less densely populated regions, putting more homes and people at risk. CAL FIRE classifies development into two WUI classes, interface and intermix, each presenting unique fire protection problems and opportunities for risk mitigation. • Interface: Interface represents dense urban development adjacent to wildland. The definable boundary between houses and wildland provides a line of defense and focuses mitigation efforts along this boundary.
• Intermix: Intermix represents sparse development interspersed within a landscape that maintains much of the wildland characteristics. Intermix areas often require fire agencies to devote resources to protect individual houses. Mitigation includes prevention efforts, fire resistant building materials, and defensible space.
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18.2 HAZARD PROFILE
18.2.1 HISTORY
Fire history is an important component in understanding fire frequency, fire type, significant ignition sources, and vulnerable areas. The history of wildfires in the County is significant. Since 1911, there has been an average of 4 wildfires a year, with an average of 17,000 acres burning annually. Historic wildfires from 1911 to 2020 in Monterey County are mapped in Figure 18-3.
Figure 18-3
Historical Wildfires in Monterey County (1911-2020)
Figure 18-3: Historical Wildfires in Monterey County (1911-2020) The Marble-Cone Fire in August 1977 burned almost 178,000 acres of land, making it the largest wildfire in recorded California history at that time. Since the Marble-Cone Fire, Monterey County has had over 50 large wildfires, listed in Table 18-2.
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Table 18-2: Large Historical Wildfires in Monterey County (1977-2020) Table 18-2
Large (Over 900 Acre) Historical Wildfires in Monterey County (1977-2020) Year Fire Name Acres
Burned Cause Year Fire Name Acres Burned Cause
2020 Carmel 6,905 Lightning 1996 Wild 25,620 Arson
2020 River 48,088 Vehicle 1994 Pinnacles 939 Unknown
2020 Dolan 124,924 Arson 1994 Basham 1,098 Unknown
2019 Lonoak 2,546 Powerline 1993 Metz 1,359 Unknown
2018 Turkey 2,225 Miscellaneous 1993 Rancho 5,415 Unknown 2017 Garza 48,887 Vehicle 1992 Unnamed 3,738 Miscellaneous 2017 Park 1,649 Equipment Use 1992 Seco 2,559 Miscellaneous 2017 Parkfield 1,816 Powerline 1992 Jolon 1,625 Arson
2016 Chimney 46,235 Vehicle 1989 Molera #2 2,745 Unknown 2016 Metz 3,876 Debris 1986 Bryant Canyon 2,428 Unknown 2016 Soberanes 132,127 Campfire 1986 Deer Valley
Ranch 1,073 Unknown
2016 Coleman 2,520 Debris 1986 Lowes 2,852 Unknown
2015 Tassajara 1,100 Arson 1986 River 5,469 Debris
2013 Pfeiffer 917 Powerline 1986 Bottcher 2,285 Campfire 2012 Turkey 2,700 Equipment Use 1985 Gorda-Rat 65,700 Lightning 2009 Bryson 2,257 Structure 1985 Wizard 5,215 Miscellaneous 2009 Gloria 6,436 Miscellaneous 1985 Unnamed 14,370 Unknown 2008 Chalk 11,200 Miscellaneous 1985 Seco 1,800 Arson
2008 Indians 81,378 Campfire 1985 Cherry 40,642 Arson
2008 Basin
Complex 162,818 Lightning 1985 Garlinger 1,078 Miscellaneous 2007 Tar 5,670 Unknown 1985 Piney Creek 1,563 Equipment Use 2006 Rico 14,507 Lightning 1981 Gonzales 4,850 Miscellaneous 2005 Johnson
Fire 1,393 Equipment Use 1980 Shirttail 2,045 Unknown
2000 Plaskett 2 5,856 Miscellaneous 1979 Nacimiento 5,371 Arson 2000 North
Fork 1,736 Equipment Use 1979 Freeman Flat 3,207 Unknown 2000 Unnamed 2,073 Non-Firefighter
Training 1979 Kaupp 1,609 Unknown
1999 Kirk 86,700 Lightning 1978 Turkey Flat 1,330 Unknown 1998 Unnamed 8,702 Non-Firefighter
Training 1978 Yost 1,619 Unknown
1996 Sur 4,410 Miscellaneous 1977 Marble-Cone 173,333 Lightning In more recent years the frequency, intensity, and impact of large wildland fires in Monterey County have increased, specifically in the Los Padres National Forest. The Basin Complex Fire, a Packet Page 501
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massive wildfire near Big Sur in 2008, burned more than 162,000 acres, destroyed 58 structures, and damaged an additional 9 structures. This fire burned the majority of the Ventana Wilderness. State and federal officials spent more than $120 million to fight the fire, making it is the most expensive fire in California history up to that time, and the second most expensive in US history. The Indians Fire during this same event period burned an additional 81,000 acres, leaving 15 structures destroyed and one damaged. These combined events made 2008 the most destructive year in recorded history for fires in Monterey County.
In December 2013, the Pfeiffer Fire burned 917 acres near Big Sur and damaged or destroyed 38 structures, including 34 residential structures and 4 outbuildings. On July 22, 2016, the Soberanes Fire began as an illegal campfire located in Garrapata State Park in Monterey County. Fed by winds and dry, unmanaged vegetation resulting from several years of extreme drought, the fire quickly spread beyond the park to threaten lives, homes, property, and the environment. It was the costliest firefight in US history, costing a total of $260 million. 2020, was another record year for fires in Monterey County, with the River, Carmel, and Dolan burning 48,000, 6,905, and 124,924 acres, respectively. Shown in Figure 18-4, the most commonly known causes of fires in Monterey County since the year 2000, are powerlines (19%), other mechanical or electrical equipment (16%), vehicles (13%), miscellaneous (12%), and arson (7%). Sometimes the cause of a fire cannot be determined, and this represents another large category, with 11% of fires in the County having an unknown cause.
Figure 18-4
Causes of Wildfires in Monterey County (2000-2020)
Figure 18-4: Causes of Wildfires in Monterey County (2000-2020) Arson
7% Campfire
2%
Debris
6%
Equipment Use
16%
Non-Firefighter
Training
3%
Miscellaneous
Powerline 12%
19%
Lightning
5%
Playing with
Fire
3%
Unknown
11%
Escaped
Perscribed
Burn
3%
Vehicle
13%
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18.2.2 LOCATION
Fire Hazard Severity Zones (FHSZ) are areas mapped by CAL FIRE that designate zones (based on factors such as fuel, slope, and fire weather) with varying degrees of fire hazard (i.e., moderate, high, and very high). While FHSZ do not predict when or where a wildfire will occur, they do identify areas where wildfire hazards could be more severe and therefore are of greater concern. The FHSZ model inputs frequency of fire weather, ignition patterns, expected rate-of spread, and past fire history. It also accounts for flying ember production based on the area of influence where embers are likely to land and cause ignitions.
Fire Hazard Severity Zones in Monterey County are mapped in Figure 18-5 Figure 18-5
Fire Hazard Severity Zones in Monterey County
Figure 18-5: Fire Hazard Severity Zones in Monterey County CAL FIRE also maps fire threat, which combines expected fire frequency with potential fire behavior. About 80% of land in Monterey County is categorized as high, very high, or extreme fire threat.
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Based on historical fire data, some portions of the County are more susceptible to wildfires, with some areas having burned 6-7 times during the recorded fire history period. The mountainous, highly combustible areas in and around the Los Padres National Forest are very susceptible to wildland fires. The communities along the Big Sur coast, including Big Sur, Post, Lucia, Gorda, and Plaskett, are also at great risk to wildland fires. Sudden Oak Death is present and expanding in this area and presents a serious and growing wildland fire danger.
Homes and property in the wildland urban interface (WUI) are likely areas of concern for future fires. Of the about 35,000 housing units located in the WUI, 38% are in an intermix zone and 62% are in an interface zone. 67 As both types of WUI account for significant area in Monterey County, mitigation strategies should address both zones.
The CAL FIRE BEU Unit Strategic Plan68 has identified the following high risk fire areas in Monterey County:
• State Highway 68 Corridor between Salinas and Monterey Peninsula / Laureles Grade • Carmel Valley, Carmel Valley Village, and Cachagua
• Carmel Highlands / Palo Colorado Canyon
• Pine Canyon (King City)
• North Monterey County / Aromas
• Jacks Peak / Pebble Beach
18.2.3 FREQUENCY
The geography, weather patterns and vegetation in the County provide ideal conditions for recurring wildfires. As noted previously, there has been an average of 4 wildfires a year, with an average of 17,000 acres burning annually. In the past 20 years, close to 750 thousand acres of the County has burned. Therefore, Monterey County is likely to face a wildland fire threat each and every year and can expect a large wildland fire to occur every few years.
Fire frequency, defined as number of times burned between 1911 and 2021 is mapped in Figure 18-6. Areas in the Los Padres National Forest, along the Big Sur coast, and the Ventana Wilderness, are the most frequently burned areas in the County, burning in some areas more than 4-5 times in the last 100 years.
67 CAL FIRE, California’s Forests and Rangelands, 2017 Assessment 68 Unit Strategic Fire Plan San Benito-Monterey, June 2020 Packet Page 504
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Figure 18-6
Fire Frequency in Monterey County
Figure 18-6: Fire Frequency in Monterey County
18.2.4 SEVERITY
As outlined in the Monterey County Community Wildfire Protection Plan69 each area of the County is unique in the various aspects that impact fire behavior. Variations in type of vegetation, slope, and microclimate weather all play a role in fire spread potential. Density of structures, road access, water supply, and available timely fire suppression resources also impact the fire spread potential. The severity of the wildland fire hazard is determined by the relationship between three factors: fuel classification, topographic slope, and critical fire weather frequency.
Fuels
Hazardous levels of fire fuels can cause fire intensities to exceed firefighting tactical ability to contain and control them. Vegetation distribution throughout the county varies by location and topography, with dramatic differences observed between coastal, valley, and inland regions. 69 Fire Safe Council for Monterey County, Monterey County Community Wildfire Protection Plan, 2010 Packet Page 505
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Dominant vegetative cover within Monterey County is herbaceous or grassland cover, distributed primarily in the low-lying valley areas along the Highway 101 corridor. While this fuel type can burn quickly under strong, dry wind patterns, it does not produce the high heat intensity and high flame lengths associated with chaparral fuel types. Other significant vegetative cover types include light brush, light grass/woodland, and hardwood litter, which are primarily associated with the steeper, upland areas in the southern, western, and northern portions of the County. Fire behavior in brush fuel types may produce flame lengths greater than 12 feet, and resistance to control may be high. Fire behavior in woodlands is variable, depending on surface fuel conditions and the presence of ladder fuels. However, crown fire is common if slope and wind conditions are favorable to allowing fire to enter the canopy.
In extreme warm/wet years, abundant precipitation and intense rainfall followed by high spring and summer temperatures rapidly dry the abundant fuels produced by the high precipitation.
Another concern within Monterey County is the presence of the Sudden Oak Death (SOD) pathogen and Pitch Canker disease. These infections can cause rapid tree mortality which can lead to a marked increase in surface fuel loads and subsequent fire behavior.
Topography
The topography of Monterey County is extremely variable, with elevations ranging from sea level to over 5,800 feet above mean sea level. Within the Salinas Valley, slopes are relatively flat across the valley floor, with elevations ranging from sea level to about 400 feet above mean sea level in the southern portions of the valley. More significant topographic variation is found in the eastern and western portions of the County, often characterized by steep slopes, deeply incised canyons, and narrow valleys. Slope measurements reach up to 175% gradients, most notably in the Los Padres National Forest located in the western portion of the County and the Gabilan Range located along the eastern County boundary. The regional topographic conditions within Monterey County have considerable effect on wildland fire behavior, as well as on the ability of firefighters to access and respond to wildfires. Steep slope and canyon alignments are conducive to channeling, deflecting, concentrating, or dispersing winds, and creating extremely erratic wildfire conditions, especially during wind driven fire events Weather
In Monterey County, the joining of marine and land air masses over uneven topography significantly compounds fire behavior. Erratic fire behavior due to rapidly shifting winds and humidity under "normal" conditions is common. During warmer and drier offshore wind flow regimes, which occur several times each year, wind patterns shift from onshore northwest to offshore east-northeast in the northern section of the County, and east-southeast in the southern portions of the County, often with above-average velocities. These conditions are associated with "Severe Fire Weather" and "Red Flag" fire warnings. Fire behavior under rare or extreme fire weather conditions constitute the greatest threat of destructive uncontrolled wildland fires, and historically are immune to planned tactical response and aggressive initial Packet Page 506
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attack. During extreme fire-weather conditions, fuel factors like age, density and moisture content may be overshadowed by weather factors such as high wind and low humidity.
18.2.5 WARNING TIME
Regardless of the circumstances that start a wildfire, warning time can be short since there is no way to predict when a wildfire might break out. Hazardous levels of fire fuels can cause fire intensities to exceed firefighting tactical ability to contain and control. High wind events that occur across much of California in autumn can create fires that are difficult to control, greatly increasing area burned and loss of life. Special attention should be paid to fires during severe wind events to improve warning time for those that might be affected or need to evacuate. Dry lightning may trigger wildfires as seen during the SCU Lightning Complex in 2020. Reliable NWS lightning warnings are available on average 24 to 48 hours prior to a significant electrical storm.
If a fire does break out and spreads rapidly, residents may need to evacuate within hours or minutes. A fire’s peak burning period generally is between 1 and 6 p.m. Once a fire has started, fire alerting is reasonably rapid in most cases. The rapid spread of cellular and two-way radio communications has contributed to a significant improvement in warning time.
In Monterey County, the safety of ingress and egress is not uniform in all areas. It is possible that some communities may become trapped without the option to evacuate, forcing them to shelter in place and defend themselves. Examples are the Big Sur coast, Palo Colorado, Partington Ridge, Los Burros Road, Cachagua, and White Rock.
18.3 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. The indirect effects of wildfires can be catastrophic.
18.3.1 WILDFIRE SMOKE
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. Smoke generated by wildfire contains visible and invisible emissions comprising particulate matter such as soot and tar; gases such as carbon monoxide, carbon dioxide, and nitrogen oxides; and toxics such as formaldehyde and 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. 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.
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18.3.2 POST -FIRE INDUCED DEBRIS FLOWS AND FLOOD FLOWS
Fires can have devastating effects on watersheds through loss of vegetation and soil erosion, which may impact the County by changing runoff patterns, increasing sedimentation, reducing natural and reservoir water storage capacity, and degrading water quality. Wildfires strip the land of vegetation and destroy forest resources. Exposed soils erode quickly and enhance siltation of rivers and streams, thereby enhancing flood potential, harming aquatic life, and degrading water quality. Wildfires can also bake soils, thus increasing the imperviousness of the ground. This increases the amount and speed of the runoff generated by storm events, further increasing the chance of flooding.
Lands stripped of vegetation are also subject to increased debris flow hazards. Slopes stripped of vegetation are exposed to greater amounts of runoff. This in turn can weaken soils and cause failures on slopes. The soils in a burn scar are highly erodible so flood waters can contain significant amounts of mud, boulders, and vegetation. For example, following the record fires in 2020, annual winter storms in 2021 caused flash floods and debris flows in the County. Fast moving mud and debris in the River Fire burn scar damaged 25 homes and injured 2 people. A large mudslide in the Dolan Fire burn scar took out a 150-foot section of Highway 1.
When wildfire-induced threats to life and safety are present, a state team of foresters, hydrologists, and geographic information systems specialists from CAL FIRE, engineering geologists from the California Geological Survey (CGS) and Regional Water Quality Control Boards (RWQCB), and civil engineers from the Department of Water Resources (DWR), can be assembled into a Watershed Emergency Response Team (WERT) to assess potential life-safety hazards from post-fire debris flows, hyper-concentrated flows, and flood flows.
An Emergency Stabilization-Burned Area Emergency Response (BAER) is a rapid assessment of burned watersheds that identifies imminent post-wildfire threats to human life and safety, property, and critical natural or cultural resources. The BAER identifies emergency stabilization measures that can be implemented before the first post-fire damaging events. BAER measures include actions such as: mulching, seeding, installation of run-off control structures, temporary barriers to protect recovering areas, and the installation of warning signs. The USGS also conducts post-fire debris-flow hazard assessments for select fires using geospatial data related to basin morphometry, burn severity, soil properties, and rainfall characteristics to estimate the probability and volume of debris flows that may occur in response to a storm.
18.4 RISK ASSESSMENT
For purposes of this analysis CAL FIRE Fire Threat data was used. Fire Threat combines expected fire frequency with potential fire behavior to create 4 threat classes, extreme, very high, high, and moderate. Wildland Fire Threat in Monterey County is mapped in Figure 18-7.
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Figure 18-7: Wildland Fire Threat
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18.4.1 POPULATION
Wildfire is of greatest concern to populations residing in the moderate, high, and very high fire hazard threat zones. US Census data was used to estimate populations within the CAL FIRE identified fire threat zones.
As seen in Figure 18-8, 306,366 people, representing 74% of the population in Monterey County live in a very high, high, or moderate fire threat zone. 35,842 people, or 9% of the total population live in a very high fire threat zone. 83,044 people, or 20% of the total population live in a high fire threat zone. 187,480 people, or 45% of the total population live in a moderate fire threat zone.
Figure 18-8
Population Exposed to Wildfire Risk
Figure 18-8: Population Exposed to Wildfire Risk
Those who live in more rural intermix areas of the County, such as the Big Sur coast, Palo Colorado, Partington Ridge, Los Burros Road, Cachagua, and White Rock may be particularly vulnerable to a wildfire due to their isolated location. It is possible these communities could become trapped without the option to evacuate, forcing them to shelter in place.
Farmworkers are particularly vulnerable to wildfire impacts because of the potential degradation of transportation infrastructure, the increased exposure to wildfire smoke while working outdoors, and direct economic effects on the agricultural industry. Because many agricultural workers are migrant and/or cannot afford to live in the County due to the lack of affordable housing, they may not be fully captured in these population numbers. 9,913
6,568
1,923
17,438
3,787
30,114
10,518 10,448
28,177
17,041
46,732
36,688
29,422
57,597
0 10,000
20,000
30,000
40,000
50,000
60,000
District 1 District 2 District 3 District 4 District 5
Monterey County Supervisorial District
Very High High Moderate
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18.4.2 PROPERTY
As summarized in Table 18-3, in Monterey County, 35,252 residential properties are in either very high, high, or moderate fire risk zones. This accounts for about $33 billion in residential property value.
Table 18-3: Residential Property Exposed to Wildfire Risk by Fire Hazard Threat Zone Table 18-3
Residential Property Exposed to Wildfire Risk by Fire Hazard Threat Zone Supervisorial
District
Very High High Moderate
# Value # Value # Value
District 1 0 $0 23 $13,604,833 324 $202,243,637
District 2 676 $391,324,023 3,138 $1,584,293,526 5,380 $2,644,748,875 District 3 1,292 $415,516,076 1,599 $474,881,281 1,372 $426,980,382 District 4 12 $94,828,547 177 $336,350,806 1,140 $862,189,835 District 5 2,469 $2,833,126,759 5,144 $5,981,555,168 12,506 $16,833,680,153 Total 4,449 $3,734,795,405 10,081 $8,390,685,614 20,722 $20,969,842,882 As summarized in Table 18-4, In Monterey County, 33,344 non-residential properties are in either very high, high, or moderate fire risk zones. This is account for about $16 billion in nonresidential property values.
Table 18-4: Non-Residential Property Exposed to Wildfire Risk by Fire Hazard Threat Zone Table 18-4
Non-Residential Property Exposed to Wildfire Risk by Fire Hazard Threat Zone Supervisorial
District
Very High High Moderate
# Value # Value # Value
District 1 0 $0 21 $29,381,019 578 $425,871,786
District 2 492 $161,328,159 1,930 $429,905,806 3,634 $1,158,346,855 District 3 4,913 $2,049,593,977 5,675 $2,626,148,904 4,422 $3,128,901,995 District 4 37 $4,709,738 219 $175,659,923 1,135 $875,700,350 District 5 1,670 $454,937,569 3,581 $1,537,735,682 5,037 $2,981,931,211 Total 7,112 $2,670,569,443 11,426 $4,798,831,334 14,806 $8,570,752,197
18.4.3 CRITICAL FACILITIES AND INFRASTRUCTURE
Critical facilities made of wood frame construction are especially vulnerable during wildfire events. In the event of a wildfire, there would likely be damage to infrastructure dependent on the severity of the wildfire and nature of the infrastructure. Most roads and railroads would sustain minimal to moderate damage except in the worst scenarios.
Power lines are the most at risk from wildfire since most transmission 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 Packet Page 511
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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.
Critical facilities of high concern and priority to protect from wildfires include communications infrastructure such as repeater sites, cell towers, radio towers, FAA communications, and the Big Sur Very High Frequency Omni-Directional Range (VOR). They are among the highest priorities to protect from wildfires.
Table 18-5 summarizes critical infrastructure in very high, high, or moderate fire risk zones.
Table 18-5: Critical Infrastructure Exposed to Wildfire Risk by Fire Hazard Threat Zone Table 18-5
Critical Infrastructure Exposed to Wildfire Risk by Fire Hazard Threat Zone Critical Infrastructure Type Very High High Moderate
Facilities
Emergency Response 0 8 7
Fire Station 1 6 4
Police Station 0 0 0
Medical Facilities 0 2 7
Military Facility 0 0 2
Large Public Facilities 0 0 0
Educational Facilities 0 3 8
Power Plant 0 0 0
Water & Wastewater Facilities 23 46 103
Stormwater Facilities 0 0 2
Government Facilities 12 14 24
Communication Facilities 498 401 253
Rain Gauges 10 15 6
Lighthouses 0 0 0
Dams 0 0 0
Hazardous Materials
Active or Idle Oil Well 735 728 284
Landfill 0 0 0
Underground Tank 1 0 1
Cal ARP Facility 0 3 1
Transportation
Airport 0 4 2
Bridge 20 53 29
Harbor 0 0 0
Highway/Freeway (Miles) 47 93 160
Driveway (Miles) 0 2 3
Major Road (Miles) 335 456 543
Local (Miles) 1,008 1,311 1,331
Railroad (Miles) 23 37 56
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18.4.4 ENVIRONMENT
Many ecosystems adapt to historical patterns of fire occurrence. These patterns, called “fire regimes,” include temporal attributes such as frequency and seasonality, spatial attributes such as size and spatial complexity, and magnitude attributes such as 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. Severe environmental impacts associated with wildfires in Monterey County include:
• 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. • 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. • Damaged Fisheries—Critical fisheries can suffer from increased water temperatures, sedimentation, and changes in water quality.
• 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—Fire can have devastating consequences for endangered species.
18.4.5 ECONOMIC IMPACT
Local economic impacts from catastrophic wildfires include the cost of fire suppression, disruptions to consumption and production of local goods and services. Immediate effects may include decreased recreation/tourism and timber harvest, as well as disruptions from evacuations and transportation delays. Other effects include direct property losses (in the form of buildings, timber, livestock, and other capital), damage to human health, and possible changes in the long-term structure of the local economy.
The tourism sector is critical economic sector in Monterey County, which is especially vulnerable to increasing risks of forest fires. The Big Sur area is a popular attraction bordering the Los Padres National Forest which is highly prone to fire risk. Big Sur was heavily impacted during the Basin Complex Fires in 2008, the Pfeiffer Fire in December of 2013, the Soberanes Fire of 2016, and the Dolan Fire in 2020. Laguna Seca is a popular recreational facility playing host to several large events throughout the year is also in a fire risk area. Increased fire threats and active wildfire will make these tourist areas less attractive, which, in turn, could negatively Packet Page 513
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impact local businesses. These may include small, medium, and large-scale businesses such as hotels, restaurants, and transportation, which are important contributors to the local economy.
Agriculture, the other key economic sector in the County, is also vulnerable to wildfire risk.
Structures, irrigation systems, and equipment, crops, livestock, and stored commodities can be lost to wildfire. Fires can also affect soil quality, which can have a ripple effect lasting many, many years. Smoke also can have many negative impacts on crops. When less sunlight reaches crops, crops develop more slowly. Less sunlight can lead to higher disease loads. When ash coats leaves and fruit, crops have even less access to light. Some crops can absorb enough smoke to change the flavor. Fires also create a high-risk environment for agricultural workers and protecting workers can delay harvest, leading to destroying overly ripe crops. There is no well-established protocol to mitigate the occupational health and safety risks associated with wildfires, which can leave workers vulnerable. In addition to the dangers of an active fire, wildfire smoke, ash, and chemicals used to treat fires negatively affect air and water quality.
18.5 FUTURE TRENDS IN DEVELOPMENT
The expansion of the wildland urban interface can be managed with strong land use and building codes. Monterey County is well equipped with these tools and this planning process has assessed capabilities with regards to the tools. As the County experiences future growth, it is anticipated that the exposure to this hazard will remain as assessed over time due to these capabilities.
18.6 ISSUES
The major issues associated with wildfire in Monterey County include 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. • Wildfires could cause landslides as a secondary natural hazard. • Climate change is likely to increase the frequency and severity of wildland fires in Monterey County.
• Future housing growth and development in the WUI should continue to be managed. • Limited water supply for firefighting in high-risk wildfire areas can limit response capabilities.
• Ingress and egress in interface and intermix areas can be limited due to a lack of road infrastructure.
• Wildfire poses a large threat to key economic sectors: Agriculture and Tourism. • Continuing and expanding hazardous fuels reduction programs. Fuel mitigation regulations hinder the ability of private property owner’s ability to reduce risk on their property.
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19. CLIMATE CHANGE
19.1 OVERVIEW
Climate is a description of long-term weather patterns. Climate change refers to any distinct change in measures of climate lasting for a long period of time, more specifically major changes in temperature, rainfall, snow, or wind patterns. Climate change may be limited to a specific region or may occur across the whole Earth. Climate change may result from:
• Natural factors, such as changes in the Sun’s energy or slow changes in the Earth’s orbit around the Sun
• Natural processes within the climate system, such as changes in ocean circulation • Human activities that change the atmosphere’s make-up, and the land surface, such as burning fossil fuels, cutting down forests, planting trees, or building developments in cities and suburb
The effects of climate change are varied and include warmer and more varied weather patterns, melting ice caps, and poor air quality, for example. Climate change will affect the people, property, economy, and ecosystems in Monterey County. 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. Increasing temperatures and rising sea-levels will have direct impacts on public health and infrastructure. Drought, coastal and inland flooding, and wildfire will continue to affect people’s livelihoods and local economies. Changing weather patterns and more extreme conditions will impact tourism and rural economies, along with changes to agriculture and crops, which are a critical backbone of Monterey County’s economic Packet Page 515
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success. There will also be negative impacts to our ecosystems, both on land and in the ocean, leading to local extinctions, migrations, and management challenges.
19.1.1 SEA LEVEL RISE
Another outcome of global climate change is sea-level rise. The sea level rose during the 20th century, and observations and projections suggest that it will rise at a higher rate during the 21st century. Rising seas increase the risk of coastal flooding, storm surge inundation, coastal erosion and shoreline retreat, and wetland loss. The cities and infrastructure that line many coasts are already vulnerable to damage from storms, which is likely to increase as sea level continues to rise and inundate areas further inland.
Globally, sea level is rising primarily because global temperatures are rising, causing ocean water to expand and land ice to melt. However, sea-level rise varies from place to place. Sealevel rise along the Pacific coast depends on the global mean sea-level rise and also on regional factors, such as ocean and atmospheric circulation patterns in the northern Pacific Ocean, gravitational and deformational effects of land ice mass changes, and tectonics along the coast.
The comparative importance of these factors determines whether local sea level is higher or lower than the global mean, and how fast it is changing which has enormous implications for coastal planning.
19.1.2 CLIMATE CHANGE AND HAZARD MITIGATION
The 2018 California State Hazard Mitigation Plan states that California is already experiencing the impacts of climate change, including prolonged drought, increased coastal flooding and erosion, and tree mortality. The state has also seen increased average temperatures, more extreme heat days, fewer cold nights, a lengthening of the growing season, shifts in the water cycle with less winter precipitation falling as snow, and both snowmelt and rainwater running off sooner in the year. The intensity of extreme weather events is also increasing. Extreme weather events and resulting hazards, such as heat waves, wildfires, droughts, and floods are already being experienced.
An essential aspect of hazard mitigation is predicting the likelihood of hazard events. Typically, predictions are based on records of past events, which assumes that the likelihood of hazard events remains essentially unchanged over time. Thus, averages based on the past frequencies are used to estimate future frequencies. 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. Information about how climate patterns are changing can increase the reliability of future hazard projections. The risk, severity, and likelihood of many hazards in Monterey County are affected by climate patterns. For this reason, an understanding of climate change is essential to efforts to effective hazard mitigation.
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A Hazard Mitigation Framework for Climate Adaptation
A hazard mitigation framework for adaptation planning creates a beneficial risk management focus for climate adaptation. The complexity and cumulative nature of climate impacts in Monterey County requires a multi-hazard approach to climate change risk. Therefore, addressing climate change in the plan as a separate hazard that will increase the risk of other hazards in this plan was determined to be the most appropriate strategy. Examples of the cumulative impacts of climate change that could affect Monterey County include:
• Wildfires are likely to increase in severity and frequency due to climate change, and more frequent and severe wildfires will release more carbon into the atmosphere exacerbating climate change.
• Precipitation variability can increase the length of fire season and worsen floods and coastal storms.
• As sea levels rise more extreme storm events will cause increased flooding impacts and increase coastal erosion rates.
• Wildfires followed by storm events increase the risk of landslides. Increased erosional forces related to sea-level rise will affect sea cliffs, creating steeper slopes while undermining the base of sea cliffs, increasing the risk and magnitude of landslides. • Exposure to wildfires, wildfire smoke, and post-wildfire events such as erosion, debris flow, and flooding can affect a watershed’s functioning and its associated ecosystem services, including water quantity and water quality. Increased sedimentation in the watershed will increase flood risk.
• Sea level rise will cause wetlands to recede reducing critical ecosystem services, including carbon sequestration, flood risk reduction, water filtration, erosion control, and groundwater recharge.
• Droughts will be more extreme and last longer due to climate change and this will have a large effect on water availability and agricultural production. Droughts increase the probability of wildfire occurrence and as fires burn more intensely, the chances heat destroys valuable topsoil increases, further affecting agriculture. Droughts decrease water availability when fire risk is highest, which could be an issue when fighting fires. • Drought can lead to groundwater overdraft, which causes land subsidence and increases the risk of seawater intrusion. Land subsidence increases sea level rise risk by creating more low-lying areas vulnerable to flooding and increasing the risk of groundwater daylighting, while seawater intrusion further reduces water supply. • Worsened hazards can affect multiple sectors of the local economy including recreation, tourism, agriculture, and forestry. Homes that are destroyed or in hazardous areas could lose value reducing homeowner’s ability to recover and effecting government revenue needed for recovery and adaptation.
In order to capture these cumulative effects and avoid maladaptation, the County decided to approach climate change resilience with a systematic multi-hazard approach.
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19.2 HAZARD PROFILE
19.2.1 HISTORY
Though climate change has not been proven solely
responsible for any disasters, past flooding,
wildfire, and drought disasters may have been
exacerbated by it. It is difficult to make direct
connections to individual disasters but increases in
both the magnitude and impact of hazards over the
last few years is likely linked to climate change.
The powerful El Niño of 2015-16 was one of the
three largest in the historical record and resulted in
winter wave energy over 25% larger than a typical
winter, driving unprecedented beach erosion that
was 45% higher than normal. 70 The impacts from
flooding and debris flows have also been
increasing. Storms in 2017 caused a record amount
of damage across the County. In 2021, storms
caused a mudslide in the burn scar left by the River
Fire that damaged 25 homes in Chualar. Flooding
also occurred near the Carmel Lagoon and the
Carmel River State Beach. The County has
experienced an increase in wildfires, with 2018,
2019 and 2020 growing the acreage of forest
burned due to extremely dry conditions. In 2020,
the River, Carmel, Dolan, and Coleman fires burned
a combined 180,000 acres.
Previous studies have indicated that important
areas and public infrastructure will be increasingly
at risk from climate change hazards. Additionally,
unlike earthquakes and floods that occur over a
finite time period, climate change is an ongoing
hazard. Many communities are already
experiencing the effects, while other effects may
not be seriously experienced for decades or may be
avoided altogether by mitigation actions taken
today.
70 California Fourth Climate Change Assessment, Central Coast Region Report Mitigation Success Story
City of Gonzales Growing Green
One of the best ways to reduce the impact
of future climate hazards is to make
progress on climate goals today. The City
of Gonzales was the first city in the County
with a certified climate action plan and has
already met its 2020 target for reducing
energy use and greenhouse gas emissions.
Gonzales harnesses the wind and sun to
reduce its carbon footprint and
demonstrates how a community can use
its stewardship of the environment as a
way of encouraging economic vitality.
Solar panels power the community pool,
police headquarters, a wastewater
treatment plant, and water wells.
Work on the environment and economy
falls under the direction of the Gonzales
Grows Green (G3) initiative. Harnessing
the strong valley breeze that arises every
afternoon, the City partnered with Taylor
Farms to build a wind turbine on City
owned land. Nonprofit developer,
Foundation Windpower, built and financed
the project and another food processor,
Mann Packing/DelMonte Fresh, will use
energy from a second wind turbine when it
opens a new plant, creating 525 jobs.
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19.2.2 LOCATION
The effects of climate change are not limited by geographical borders. Monterey County, the State of California, the United States, and the rest of the world are all at risk of climate change.
As such, the entire County is at risk to the effects of climate change.
19.2.3 FREQUENCY
In terms of how likely and quickly impacts will occur, temperature related impacts are the most likely near-term climate change exposure facing the County and should be addressed and prioritized in future adaptation planning efforts. While sea-level rise has a high certainty rating and is already occurring, its onset is not expected to occur until closer to the end of the century in terms of changes in areas already vulnerable to flooding or causing permanent inundation in tidally influenced areas of the County. Addressing increases in flooding and wildfire risk have mid-term onsets and should be prioritized accordingly.
19.2.4 SEVERITY
The State of California has been taking action to address climate change for over 20 years, focusing on both greenhouse gas emissions reduction and adaptation. The California Adaptation Planning Guide (APG) provides guidance and support for communities addressing the unavoidable consequences of climate change. The California Fourth Climate Change Assessment 71 identifies the following climate change impacts of concern to the Central Coast:
• Maximum and minimum temperatures will continue to increase through the next century, with greater increases in inland areas. Precipitation is expected to increase slightly, but precipitation variability will increase substantially • Projected future droughts are likely to be a serious challenge to already stressed water supplies. Higher temperatures may result in increases in water demand for agriculture and landscaping. Reduced surface water will lead to increases in groundwater extractions that may result in increased seawater intrusion. Lower surface flows will lead to higher pollutant concentrations and will impact aquatic species. • Impacts to the region’s public health include increases in heat-related illnesses for agricultural workers, harmful particulate matter from wildfires, and an increase in ground-level ozone. Infectious/Vector-borne diseases include an increase in Valley Fever and Pacific Coast tick fever, and an increase in harmful algal blooms will have detrimental effects on animals and people exposed to toxins released from the algae. • Agricultural production is highly sensitive to climate change, including amounts, forms, and distribution of precipitation, changes in temperatures, and increased frequency and intensity of climate extremes. The Salinas Valley is identified as one of the most vulnerable agricultural regions under climate change.
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• Periodic El Niño events dominate coastal hazards while atmospheric rivers, expected to increase, are the dominant drivers of locally extreme rainfall events. • Recently observed and projected acceleration in sea level rise poses a significant threat to coastal communities. Future flooding is also a serious concern. • Estuarine systems will be affected by accelerated sea level rise, warming of water and air, ocean acidification, and changes in runoff. Some marshes may drown or become shallow mudflats, leading to a loss of the ecosystem services that marshes provide. • Many beaches will narrow considerably. As many as two-thirds will be completely lost over the next century, along with the ecosystems supported by those beaches. The landward erosion of beaches will be driven by accelerating sea level rise combined with a lack of ample sediment, effectively drowning the beaches between the rising ocean and the backing cliffs and/or urban hardscape.
• Frequent and sometimes large wildfires will continue to be a major disturbance and post-fire recovery time may be lengthened.
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.
Climate change projections contain inherent uncertainty, largely derived from the fact that they depend on future greenhouse gas emission scenarios. Generally, the uncertainty in greenhouse gas emissions is addressed by the presentation of differing scenarios. Uncertainty in outcomes is generally addressed by averaging a variety of model outcomes.
Despite this uncertainty, climate change projections present valuable information to help guide decision-making for possible future conditions. Representative concentration pathways, or RCPs, are different scenarios for the future severity of climate change. The following sections summarize information developed for the County by Cal-Adapt, a resource for public information on how climate change might impact local communities, based on the most current data available. The projections are averaged across the countywide planning area and include information from two emissions scenarios, which were developed by the IPCC:
• Medium Emissions Scenario (RCP 4.5): Emissions peak around 2040 and then decline • High Emissions Scenario (RCP 8.5): Emissions continue to rise strongly through 2050 and plateau around 2100
Temperature
The historical (1961-1990) average maximum temperature in Monterey County was 70.1°F and the average minimum temperature was 41.5°F. While average temperatures may fluctuate from year-to-year, and may differ from one municipality to the next, the trend for the County indicates that average temperatures are increasing. By Mid-Century, average annual maximum temperatures are expected to increase 3.4°F – 4.2°F, depending on the emissions scenario. By Packet Page 520
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the end of the century, annual maximum temperatures could increase 4.5°F – 7.4°F. Predicted changes in annual average minimum and maximum temperatures in Monterey County is summarized in Table 19-1.
Table 19-1: Predicted Change in Annual Average Temperatures in Monterey County Table 19-1
Predicted Change in Annual Average Temperatures in Monterey County (Cal Adapt) Emissions Scenario
Average Minimum Temperatures Average Maximum Temperatures Change 30-Year
Average
30-Year
Range Change 30-Year Average
30-Year
Range
Baseline (1961-1990)
Modeled Historical - 41.7 °F 41.0 - 42.3 °F - 70.0 °F 69.5 - 70.5 °F Mid-Century (2035-2064)
Medium Emissions (RCP 4.5) +3.1 °F 44.8 °F 43.1 - 46.2 °F +3.4 °F 73.4 °F 71.8 - 74.8 °F High Emissions (RCP 8.5) +3.9 °F 45.6 °F 43.9 - 47.1 °F +4.2 °F 74.2 °F 72.3 - 76.1 °F End-Century (2070-2099)
Low Emissions (RCP 4.5) +4.1 °F 45.8 °F 43.5 - 47.7 °F +4.5 °F 74.5 °F 72.4 - 76.9 °F High Emissions (RCP 8.5) +7.0 °F 48.7 °F 45.8 - 51.5 °F +7.4 °F 77.4 °F 74.6 - 81.4 °F Figure 19-1 shows the projected increases in average temperatures in Monterey County under various climate change scenarios.
Figure 19-1
Projected Increase in Average Temperature in Monterey County Figure 19-1: Projected Increase in Average Temperature in Monterey County 50 52
54 56
58 60
62 64
66 68
Degrees Farenheit
Year
Historical
Average
Temperature
Medium
Emissions
Average
Temperature
High Emissions
Average
Temperature
Source: Cal-Adpat,
LOCA Downscaled
CMIP5 Climate
Projections, 4 priority
GCMs (HadGEM2-ES,
CNRM-CM5,
CanESM2, MIROC5)
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Extreme Heat
Extreme hot temperatures are likely to become more common. The extreme heat day temperature threshold for Monterey County is 92.5°F. The historical average (1961-1990) number of extreme heat days is 4 days. By Mid-Century, there are projected to be an annual average of 8-11 days with temperatures over the extreme heat day threshold. By the end of the century, there are projected to be an annual average of 12-24 days per year with temperatures over the extreme heat day threshold.
Figure 19-2 shows the projected increases in extreme heat days in Monterey County under various climate change scenarios.
Figure 19-2
Projected Increase in Extreme Heat Days in Monterey County Figure 19-2: Projected Increase in Extreme Heat Days in Monterey County Precipitation
Projections of changes in precipitation are more nuanced than projected changes in temperature and have less separation between emissions scenarios. There is a projected increase of year-to-year variability with wetter days during periods of precipitation, but with fewer total days with precipitation. Average annual precipitation under RCP8.5 shows significant increases by 2100. Precipitation is generally expected to increase throughout Monterey County. Historical annual average precipitation in Monterey County is 19.3 inches and annual average precipitation is projected to increase by 1.8 to 5.1 inches annually.
While average precipitation is expected to increase by a relatively small amount, annual variability increases substantially by the end of the century. Projections suggest that extremely 0 5
10 15
20 25
30 35
40 Number of Extreme Heat Days
Year
Modeled
Historical
Medium
Emissions
Scenario
High
Emissions
Scenario
Source: Cal-Adpat,
LOCA Downscaled
CMIP5 Climate
Projections, 4 priority
GCMs (HadGEM2-ES,
CNRM-CM5,
CanESM2, MIROC5)
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wet and dry years may become more severe, and that the wettest day of the year will become wetter relative to historical conditions.
Fog
A key feature of the Coastal regions of Monterey County is summertime coastal fog and low clouds. Low clouds reflect solar radiation, which cools the land surface. Fog droplets also add water to coastal systems. The landscape pattern of coastal fog and low clouds is remarkably stable. Low elevation sites and valleys that are open to northwest summer winds, such as Salinas Valley and Monterey Peninsula, average 15 hours/day of summertime fog and low cloud cover annually. Agriculture benefits when fog and low clouds reduce evapotranspiration rates, reducing crop demand for water and irrigation.
The future of coastal fog under climate change remains uncertain. Coastal fog formation and onshore transport are a result of complex feedbacks between ocean, air, and land systems and provide a unique focal point to better understand global to local climate change dynamics.
19.2.5 WARNING TIME
As this section has described, many existing hazards could be intensified as a result of climate change, decreasing warning times and exacerbating impacts. Warning times are discussed under the various other hazards. Other climate change impacts are more long-term; scientists have a high confidence in predicting the rise in global temperatures and have reached a consensus on the future impacts of climate change and the time frame in which they will occur.
19.3 RESPONSES TO CLIMATE CHANGE
Communities and governments worldwide are working to address, evaluate and prepare for climate change impacts that are likely to affect 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 the term’s meaning changes across disciplines:
• Mitigation in emergency management - as generally addressed in this hazard mitigation plan - is typically defined as the effort to reduce loss of life and property by lessening the impact of disasters.
• Mitigation in climate change discussions is defined as a human intervention to reduce impacts on the climate system. It includes strategies to reduce greenhouse gas sources and emissions and enhance greenhouse gas sinks.
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.
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harm or exploit beneficial opportunities. 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. Some initiatives and actions can both reduce greenhouse gas emissions and support adaptation to likely future conditions.
Societies across the world are facing the need to adapt to changing conditions associated with natural disasters and climate change. 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 is the potential or ability of a system, region, or community to adapt to the effects or impacts of climate change. Enhancement of adaptive capacity represents a practical means of coping with changes and uncertainties in climate, including variability and extremes.
Adaptive capacity goes beyond human systems, as some ecosystems are able 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 climate action planning efforts of the planning partners are included in the jurisdiction-specific annexes in Volume 2.
19.3.1 COMMUNITY RESILIENCE
Adaptation and resilience are not the same thing, although they are related. As noted previously, adaptation refers to adjustments in natural or human systems in response to the actual or anticipated effects of climate change and associated impacts. Resilience is the capacity of any entity - an individual, a community, an organization, or a natural system - to prepare for disruptions, to recover from shocks and stresses, and to adapt and grow from a disruptive experience. A community’s resilience is determined by its ability to survive, adapt, and thrive no matter what acute shock or chronic stressor it experiences. Put simply, adaptation is an action or set of actions, and resilience describes a desired outcome.
Flooding, drought, and other climate-hazards increase risk to already vulnerable populations.
Becoming more resilient by anticipating and addressing community threats, holds the potential to save lives, to save billions in recovery dollars and economic losses, and encourages social equity and connectedness, fostering communities that grow and recover in ways that make them stronger than before.
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Monterey County is taking steps to prepare for the impacts of a changing climate and a series of adaptive steps can greatly contribute to resilience. In a resilient Monterey County:
• Built infrastructure systems can withstand changing conditions and shocks, including changes in climate conditions, while continuing to provide critical services. • People and communities can respond to changing average conditions, shocks, and stresses in a manner that minimizes risks to public health, safety, and economic disruption; and maximizes equity and protection of the most vulnerable so that they do not simply survive climate-related events but thrive after these events. • Natural systems can adjust and maintain functioning ecosystems in the face of change.
The Monterey County Community Resilience Plan is a countywide framework outlining the challenges and opportunities to building a more resilient Monterey County. Through the resilience assessment and community discussions, Monterey County has identified six strategies to build community resilience and address the unpredictable impacts of environmental, social, and economic shocks and stresses.
Strategy 1: Build Social Capital
Social capital encompasses the social networks, associations, and the trust that they generate among groups and individuals within the community. Social capital has the potential to contribute to resilience by enhancing sense of belonging and strengthening bonds between individuals and groups within communities. By building social capital and creating a strong sense of community, Monterey County can build a network of social support, which can help the community work together to be more prepared before, during, and after disasters. A socially connected community is more resilient and better able to withstand disasters and foster community recovery.
Strategy 2: Enhance Emergency Services Infrastructure
Emergency preparedness, response, and recovery, efforts can help protect the community from the impacts of disasters. Enhancing emergency services infrastructure can make it easier to withstand, respond to and recover from emergencies. Further, advanced planning for critical facilities and infrastructure, transportation, and communication systems can make response and recovery efforts easier. For communities to function and prosper, they need buildings and infrastructure systems that are operational. When buildings and infrastructure systems are damaged, social services frequently are interrupted, economic losses soar, and resources must be re-allocated to repair and rebuild. Continual improvements in preparedness in response to threats and disruptions will build a stronger and more resilient Monterey County.
Strategy 3: Move Toward Sustainability
Resilience and sustainability represent complementary values. Sustainability is the ability to continue important functions indefinitely without a decline in quality. Resilience is the ability to thrive in the face of change. Together, these two concepts identify a key social, economic, and environmental goal: to create systems that enhance, rather than degrade, the world around Packet Page 525
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them, and in turn that can withstand inevitable shocks from environmental and technological changes.
Strategy 4: Create Healthy Communities
Health, meaning physical, behavioral, social, and environmental health and wellbeing, is a big part of overall resilience. In many ways, health is a key foundation of resilience because almost everything done to prepare for disasters and protect infrastructure is ultimately in the interest of preserving human health and welfare. A resilient community has accessible health systems that are able to withstand disasters. The community can take collective action after an adverse event because it has developed resources that reduce the impact of major disturbances and help protect people’s health. Resilient communities promote individual and community physical, behavioral, and social health to strengthen their communities for daily, as well as extreme, challenges.
Strategy 5: Encourage Resilient Households
A resilient community has the capacity, resources, and tools necessary to prepare for, withstand, and respond to system shocks and unexpected events, and this can start at the household level. Preparing families and households to anticipate the impacts of natural hazards and disasters, will increase their ability to persevere through the event and get back to normal life as quickly as possible.
Strategy 6: Empower Social Mobility
A resilient community understands that hazards and disasters have disproportionately adverse impacts on vulnerable populations (including economically disadvantaged, racial and ethnic minorities, the uninsured, low-income children, and elderly residents, the homeless, and those with chronic health conditions) and works to understand and meet the needs of all.
19.4 RISK ASSESSMENT - SEA LEVEL RISE
This Plan highlights sea-level rise within the climate change section because this hazard has delineated hazard boundaries and quantifiable exposure and damage estimations directly related to climate change.
While flooding already poses a risk in Monterey County, rising seas will put new areas at risk and increase the likelihood and intensity of floods in areas already at risk. Rising sea levels will affect Monterey County in several ways including increased tidal inundation, coastal erosion, tsunami inundation, and seawater intrusion, as well as worsened storm surge leading to increased coastal and fluvial flooding. Coastal levees and flood control structures will be undersized to manage the combined influences of higher flow events and sea level rise. Erosion of barrier dunes will expose previously protected areas to flooding.
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Under medium to medium‐high emissions scenario, projections indicate mean sea level along the coast of Monterey County could rise close to 5 feet by 2100. 72 The current sea level rise
projections for the Monterey Tide Gauge are summarized in Table 19-2.
Table 19-2: Monterey Tide Gauge Projected Sea Level Rise (in Feet) Table 19-2
Monterey Tide Gauge Projected Sea Level Rise (in feet)
Year Low Risk Aversion1* Medium-High Risk Aversion2* Extreme Risk Aversion** Upper Limit of Likely 1-in-200 Chance Single Scenario
2030 0.5 0.8 1.0
2040 0.8 1.2 1.7
2050 1.1 1.9 2.7
2060 1.4 2.6 3.8
2070 1.8 3.4 5.1
2080 2.3 4.4 6.6
2090 2.8 5.5 8.2
2100 3.3 6.9 10.1 1 ~17% probability sea level rise exceeds number listed 2 0.5% probability sea level rise exceeds number listed * Probabilistic Projections (in feet) (based on Kopp et al. 2014) ** H++ Scenario, no associated probability (Sweet et al. 2017) While mean sea level will rise across the County, it is relative. Locational differences in elevation between the height of the sea surface and the height of the land surface will lead to a variation in the risks posed to communities and ecosystems from coastal flooding. Relative sea level rise across the County will be determined by vertical land motion, changes in the height of the geoid (the gravitationally determined surface of the ocean in the absence of tides and ocean currents), and changes in the height of the sea surface relative to the geoid. Additionally, land use patterns and development, flood control structures, habitat, and geomorphology vary greatly. Therefore, the change in relative sea level will vary across the County coastline.
Sea level rise risk exposure was calculated based on the NOAA Office for Coastal Management’s sea level rise projections. 73 Based on NOAA’s scenarios, Figure 19-3 shows the potential inundation coastal areas from projected 1 to 10 feet sea level rise above the current Mean Higher High Water (MHHW) condition.
Three sea level rise levels (25 cm, 75 cm, and 200 cm) were chosen to represent planning horizons based on Ocean Protection Council (OPC) Sea Level Rise Projections for the Monterey Tide Gauge. 25 cm of sea level rise represents near term (2030) risk, 75 cm represent mid-term (2060) risk, and 200 cm represent long-term (2100) risk. This assessment is based on current conditions and does consider any adaptation or mitigation measures that may be taken in the coming decades.
72 State of California Sea-Level Rise Guidance, Ocean Protection Council (2018) 73 Sea Level Rise Viewer, NOAA Office for Coastal Management Packet Page 527
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Figure 19-3: Sea Level Rise Risk
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19.4.1 POPULATION AND PROPERTY
Table 19-3, Table 19-4, and Table 19-5 summarize people and property that will be exposed to sea level rise risk in the Supervisorial District 2, 4, and 5, respectively. Districts 1 and 3 are not located on the coast and were not considered exposed to sea level rise risk.
Table 19-3: Population and Property Exposed to Sea Level Rise Risk in District 2 Table 19-3
Population and Property Exposed to Sea Level Rise in Monterey County District 2 Sea Level Rise Amount Population Residential Property Non-Residential Property # Value # Value
1 ft Sea Level Rise (2030) 2,129 39 $12,796,994 1,342 $153,665,283 3 ft Sea Level Rise (2060) 2,570 54 $19,137,706 1,449 $212,686,695 7 ft Sea Level Rise (2100) 7,000 294 $140,045,288 1,757 $334,589,838 Table 19-4: Population and Property Exposed to Sea Level Rise Risk in District 4 Table 19-4
Population and Property Exposed to Sea Level Rise in Monterey County District 4 Sea Level Rise Amount Population Residential Property Non-Residential Property # Value # Value
1 ft Sea Level Rise (2030) 85 1 $170,236 73 $172,367,581 3 ft Sea Level Rise (2060) 85 1 $170,236 78 $173,380,493 7 ft Sea Level Rise (2100) 127 4 $1,443,035 96 $199,664,235 Table 19-5: Population and Property Exposed to Sea Level Rise Risk in District 5 Table 19-5
Population and Property Exposed to Sea Level Rise in Monterey County District 5 Sea Level Rise Amount Population Residential Property Non-Residential Property # Value # Value
1 ft Sea Level Rise (2030) 1,056 165 $901,001,664 391 $463,086,630 3 ft Sea Level Rise (2060) 1,070 183 $1,044,954,182 418 $593,512,581 7 ft Sea Level Rise (2100) 1,830 218 $1,212,814,204 708 $747,868,671 It is also important to consider the combined effect of sea level rise with worsened storm surge.
During a 1% annual chance flood, 5 feet of sea level rise would leave around 14,000 people and $2.2 billion in property vulnerable to flooding in the County. 74 Coastal Storm Modeling System (CoSMoS) expands and improves on earlier sea level rise studies by dynamically modeling storm and sea level rise scenarios across California, and incorporating fluvial discharge, ocean swell, storm surge, and sea level anomalies (as during El Niño). CoSMoS modeling indicates some areas will be increasingly vulnerable to the cumulative impacts of sea level rise.
74 California Climate Change Center, The Impacts of Sea Level Rise on the California Coast (May 2009) Packet Page 529
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For example, as seen in Figure 19-4, with 1.6 feet of sea level rise flood extent in the Moss Landing area will vary based on the storm magnitude.
Figure 19-4
1.6 Feet Sea Level Rise in the Moss Landing Area with Various Storm Scenarios (CoSMoS) Figure 19-4: 1.6 Feet Sea Level Rise in Moss Landing with Various Storm Scenarios
19.4.2 CRITICAL FACILITIES AND INFRASTRUCTURE
Some critical infrastructure and facilities are at increased risk of coastal flooding in the County due to sea level rise. Portions of Highway 1 in the northern end of the County will become increasingly vulnerable to sea level rise risk. Critical facilities and other important assets may be damaged by temporary inundation, resulting in loss of services such as power or wastewater treatment.
Table 19-6 summarizes critical infrastructure exposed to sea level rise risk.
Table 19-6: Critical Infrastructure Exposed to Sea Level Rise Risk Table 19-6
Critical Infrastructure Exposed to Sea Level Rise Risk
Critical Infrastructure Type 1 ft Sea Level Rise
(2030)
3 ft Sea Level Rise
(2060)
7 ft Sea Level Rise
(2100)
Facilities
Emergency Response 0 0 0
Fire Station 0 0 0
Police Station 0 0 0
Medical Facilities 0 0 0
Military Facility 0 0 0
Large Public Facilities 0 0 0
Educational Facilities 0 1 2
Power Plant 0 0 0
Water & Wastewater Facilities 1 1 11
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Table 19-6
Critical Infrastructure Exposed to Sea Level Rise Risk
Critical Infrastructure Type 1 ft Sea Level Rise
(2030)
3 ft Sea Level Rise
(2060)
7 ft Sea Level Rise
(2100)
Stormwater Facilities 0 0 3
Government Facilities 0 0 0
Communication Facilities 4 7 17
Rain Gauges 0 1 0
Lighthouses 0 0 0
Dams 0 0 0
Hazardous Materials
Active or Idle Oil Well 2 3 4
Landfill 0 0 0
Underground Tank 0 0 0
Cal ARP Facility 0 0 0
Transportation
Airport 0 0 0
Bridge 8 0 9
Harbor 3 3 3
Highway/Freeway (Miles) 0.2 2 36
Driveway (Miles) 0 0 0
Major Road (Miles) 8 12 49
Local (Miles) 6 9 20
Railroad (Miles) 3 1 9
As noted previously, it is also important to consider the combined effect of sea level rise with worsened storm surge. During a 1% annual chance flood, 5 feet of sea level rise would leave around 141 miles of highways and roads, and 23 miles of railway vulnerable to flooding in the County. 75
19.4.3 ENVIRONMENT
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. Seawater 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.
Monterey County contains many important protected habitats, including the Monterey Bay National Marine Sanctuary, the largest marine protected area in the United States, as well as the Elkhorn Slough State National Estuarine Research Reserve, the Moss Landing State Wildlife Area, the Moro Cojo State Marine Reserve, and the Salinas River Dunes Natural Wildlife Refuge. 75 California Climate Change Center, The Impacts of Sea Level Rise on the California Coast (May 2009) Packet Page 531
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The Elkhorn Slough, a unique tidal salt marsh, provides critical habitats for many species, including a large variety of aquatic birds, marine invertebrates, and fish, as well as sea otters, sea lions, and harbor seals. Biodiversity in the Elkhorn Slough is among the highest in the US.
The Moro Cojo Slough and Old Salinas River also provide important habitats for threatened species. This is currently the third largest extent of estuarine marsh in the State, but around 85% is at risk of degradation and could become open water due to sea level rise. Researchers have estimated the slough and the adjacent Moss Landing Harbor area host roughly 5% of the statewide population of sea otters. 76 These areas likely will play an important role in the recovery of the California sea otter population and therefore conservation of this area is particularly important. Beach dunes provide important habitat for many native plants and animals, including the western snowy plover, western fence lizard, beach wild rye, and many more species. Loss of coastal dunes means loss of important habitat for species as well as loss of an important protective buffer.
19.4.4 ECONOMIC IMPACT
Sea level rise will impact the local economy. Tourism is a major economic driver in Monterey County, and future sea level rise could threaten popular beaches and recreational facilities. Sea level rise could affect vertical and lateral beach access points, which would prevent residents and visitors from accessing the beach and may increase the risk of injuries.
Beach tourism is important to the County’ economy and generates significant revenue as many visitors rent hotels or other accommodations, dine out or shop at area stores. Visitor-serving areas such as those on the Monterey Peninsula and in Big Sur include local businesses and hotels that benefit the local economy. These businesses depend on tourism, and cities and communities within the County benefit from sales tax revenues. Disruption of these areas due to impacts of sea level rise could decrease economic activity and affect the local economy.
Future sea level rise in the County may also negatively impact coastal businesses and households and decrease coastal real estate opportunities. 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.
Sea level rise is also likely to increase the risk of flooding in the lower Salinas Valley. This could lead to the flooding on large swaths of agricultural land and threaten a major economic driver.
Sea level rise in addition to coastal storms and erosion impacts could lead to severe flooding and inundation of economically important infrastructure such as harbors and buildings related to commercial and recreational fisheries.
76 Elkhorn Slough, Technical Report Series
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19.5 RISK ASSESSMENT - HAZARDS OF CONCERN
This section discusses the increased risk posed by specific hazards previously profiled in this plan that were identified as likely to increase in impact due to climate changes. 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 Monterey County.
19.5.1 AGRICULTURAL EMERGENCIES
The Salinas Valley is identified as one of the most vulnerable agricultural regions under climate change. 77 The amounts, forms, and distribution of precipitation, as well as the increased frequency and intensity of climate extremes, will affect water availability as well as pests, crop yields, and the length of the growing season.
Many weeds, pests, and fungi thrive under warmer temperatures, wetter climates, and increased CO2 levels. The ranges and distribution of weeds and pests are likely to increase with climate change. This could cause new problems for farmers' crops previously unexposed to these species. Plant and livestock diseases are also affected by temperature related climate factors. 78 Warmer temperatures could allow some parasites and pathogens to survive more easily and increased rainfall, moisture-reliant pathogens could thrive. 79 For any particular crop, the effect of increased temperature will depend on the crop’s optimal temperature for growth and reproduction. Many permanent crops are sensitive to small temperature changes during development stages and/or close to harvest. Threshold temperature impacts can affect dairy production and wine grape quality. For example, the yields for wine grapes and strawberries may be reduced due to warm winters. 80 Extreme events, especially floods and droughts, can harm crops and reduce yields. Dealing with drought could become a challenge in areas where rising summer temperatures cause soils to become drier. Heat could also directly threaten livestock. Heat stress affects animals both directly and indirectly. Over time, heat stress can increase vulnerability to disease, reduce fertility, and reduce milk production.
Climate change also has the potential to impact water availability. It may cause farmers to change the crops they plant, affecting water demand and the amount of water they apply.
Adaptation options to shift varieties or locations of production would require significant time 77 Vulnerability and Adaptation to Climate Change in California Agriculture, California Energy Commission 78 Preliminary Review of Adaptation Options for Climate-Sensitive Ecosystems and Resources, US Climate Change Science Program and the Subcommittee on Global Change Research (2008) 79 The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity in the United States, US Climate Change Science Program and the Subcommittee on Global Change Research (2008) 80 Ch. 6: Agriculture. Climate Change Impacts in the United States: The Third National Climate Assessment, US Global Change Research Program (2014)
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and capital investment. Climate change could also impact agriculture in the region by increasing the demand for irrigation to meet higher evaporative processes. Monterey County is highly reliant on groundwater for agricultural operations. As climate change exacerbates drought conditions overdraft of the aquifers is likely to increase. Seawater intrusion is already a major threat to groundwater supply, and this is likely to increase as sea levels rise.
19.5.2 COASTAL EROSION
Sea level rise is likely to increase rates of coastal erosion due to the increase in the frequency, severity, and duration of high tides and wind-driven waves associated with severe storms.
Higher sea level will expose beaches, cliffs, and coastal dunes to more persistent erosional forces. High tides may also coincide with heavy rain exacerbating coastal flooding, coastal erosion, and landslides, such as were experienced during the 1998 and 2016 El Nino storms. 81 Over the next 50 years, sea level rise is predicted to increase coastal erosion 20-25% over historic erosion rates and in the 50-100-year timeframe, erosion rates are projected to increase an additional 40-50% over historic rates. 82
To determine coastal erosion risk, USGS Pacific Coastal and Marine Science Center CoSMos shoreline change, and cliff retreat projection data was used. For cliff retreat modeling an end of century (2100) forced sea level rise amount of 200 cm was used. For shoreline change, winter erosion uncertainty modeling was used to capture the degree of uncertainty associated with future shoreline erosion. Hold the Line scenario modeling was chosen for both types of erosion.
Three sea level rise levels (25 cm, 75 cm, and 200 cm) to represent planning horizons based on OPC Sea Level Rise Projections for the Monterey Tide Gauge. 25 cm of sea level rise represents near term (2030) risk, 75 cm represent mid-term (2060) risk, and 200 cm represent long-term (2100) risk. Table 19-7 summarizes coastal erosion risk in Monterey County based on sea level rise scenario and erosion type.
Table 19-7: Population and Property Exposed to Coastal Erosion Risk Table 19-7
Population and Property Exposed to Coastal Erosion Risk in Monterey County Sea Level Rise Scenario/
Erosion Type Population Residential Property Non-Residential Property # Value # Value
Cliff Erosion
Sea Level Rise (25 cm) 1,027 206 $1,183,367,352 226 $221,988,454 Sea Level Rise (75 cm) 1,642 226 $1,244,106,508 227 $223,536,860 Sea Level Rise (200 cm) 1,932 253 $1,323,971,611 248 $240,099,182 Shoreline Erosion
Sea Level Rise (25 cm) 489 4 $3,099,857 24 $196,070,566 Sea Level Rise (75 cm) 213 4 $3,099,857 54 $196,070,566 Sea Level Rise (200 cm) 213 4 $3,099,857 49 $190,008,411 81 Governor’s Office of Emergency Services (Cal OES), State of California Hazard Mitigation Plan 82 Association of Monterey Bay Area Governments, Coastal Regional Sediment Management Plan Packet Page 534
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19.5.3 DAM AND LEVEE FAILURE
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, including 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.
For levees, a reduction in freeboard caused by a changing hydrograph means that a levee may no longer protect an area against the design-storm standard for which it was originally built (for example 1-%-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.
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.
Climate change could lead to increases in flood flows, which would result in that water infrastructure, such as dams, would need to manage flows for which they were not designed.
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. Climate change will likely impact the ability of dam operators to estimate extreme flood events.
19.5.4 DROUGHT
With a warmer climate, droughts could become more frequent, more severe, and longer lasting. While climate models tend to differ about future precipitation trends and their magnitudes in California, projections show an increase in extreme dry events and only modest changes in mean precipitation. When combined with increasing temperatures, even minor fluctuations will increase pressure on Monterey County’s water resources, which are already over-stretched by the demands of a growing agriculture economy and population. Existing local surface storage and groundwater recharge will become less reliable and more expensive.
Decreasing snowmelt and spring stream flows coupled with increasing demand for water resulting from both a growing population and hotter climate could lead to increasing water shortages.
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Some areas could experience longer, more intense droughts, resulting from higher summer temperatures and reduced precipitation. Reduction in precipitation coupled with heat stress could adversely impact crop production and dry out soils. Drought may threaten pasture and feed supplies. Drought reduces the amount of quality forage available to grazing livestock. For animals that rely on grain, changes in crop production due to drought could also become a problem. Drought is likely to lead to reduced water supplies, leaving less water available for irrigation when more is needed.
More extreme droughts and higher temperatures will also alter the natural recharge of groundwater and potentially exacerbate groundwater overdraft. Reduced groundwater storage limits the use of groundwater as a backup supply during drought. One of the most persistent water quality problems in the region, the intrusion of salt water into groundwater aquifers and wells, could potentially increase under climate change depending on the implementation of adaptation projects.
19.5.5 EARTHQUAKE
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. The study found that as glaciers melt, they lighten the load on the Earth's crust. Tectonic plates, which are mobile pieces of the Earth's crust, can then move more freely. 83
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 hydrograph could fail during seismic events.
19.5.6 FLOODING
Scientist’s project greater storm intensity with climate change, resulting in more direct runoff and flooding. High frequency flood events in particular will likely increase with a changing climate. What is currently considered a 1-%-annual-chance flood may also strike more often, leaving many communities at greater risk. Extreme atmospheric river events, the dominant driver of locally extreme rainfall events and associated flooding, are expected to increase under projected climate change.
83 Retreating Glaciers Spur Alaskan Earthquakes, NASA (August 2004) Packet Page 536
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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 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.
19.5.7 HUMAN CAUSED HAZARDS
Studies have linked high temperatures with increases in intense violence. 84 Increasing evidence indicates that climate change is causally associated with collective violence, generally in combination with other factors. Increased temperatures and extremes of precipitation with their associated consequences, including resultant scarcity of cropland and other key environmental resources, are major pathways by which climate change leads to collective violence. 85
Large-scale human migration due to resource scarcity, increased frequency of extreme weather events, and other factors is likely to increase with climate change. Populations in communities with worsening conditions may consider moving to better places, provided the costs of migration are affordable. However, sudden climatic changes or natural disasters might lead, in the absence of alternatives, to migration choices which are forced rather than the result of a well-planned process. The exact impact of climate induced migration is uncertain at this time.
More favorable areas are likely to see increases in population, while other areas see dramatic decreases.
19.5.8 PUBLIC HEALTH HAZARDS
Increased temperatures that manifest as heat waves directly harm human health through heatrelated illnesses and the exacerbation of pre-existing conditions in vulnerable populations. Heat waves are defined as five days over 79°F to 85°F along the coast and 99°F to 101°F inland.
Coastal areas should expect one more heat wave per year by 2050 and four to eight more per year by 2100. Inland, three to four more heat waves are expected to 2050 and eight to ten more per year in 2100. 86 Some populations in Monterey County are especially vulnerable to the effects of more frequents extreme heat events. Heat waves and prolonged heat days in the 84 Heat and Violence, Craig A. Anderson, Current Directions in Psychological Science (February 2001) 85 Climate Change and Collective Violence, Barry S. Levy, Victor W. Sidel, and Jonathan A. Patz, Annual Review of Public Health (March 2017) 86 Climate Change and Health Profile Report: Monterey County, California Department of Public Health (February 2017)
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area would increase the exposure of thousands of outdoor workers to heat related illnesses, including vulnerable populations such as agricultural field workers.
Rising temperatures and more extreme drought events are increasingly associated with an uptick in vector-borne and infectious disease transmission. Climate is one of the factors that influence the distribution of diseases borne by vectors (such as fleas, ticks, and mosquitoes), which spread pathogens that cause illness. The geographic and seasonal distribution of vector populations, and the diseases they can carry, depends not only on climate but also on land use, socioeconomic and cultural factors, pest control, access to health care, and human responses to disease risk, among other factors. Daily, seasonal, or year-to-year climate variability can sometimes result in vector/pathogen adaptation and shifts or expansions in their geographic ranges. Such shifts can alter disease incidence depending on vector-host interaction, host immunity, and pathogen evolution. Additionally, lack of soil moisture due to drought and evaporation from high temperatures increases dust particle concentration, which sometimes house harmful fungal spores and viruses. 87
Cases of vector-borne disease, including Lyme disease, are expected to rise with climate change. A newly identified vector-borne disease, Pacific Coast Tick Fever, is spread by Dermacentor occidentalis, which harbors Rickettsia philipii, the causative agent of the disease.
Although still an emerging illness, a few of the human cases originated in the Central Coast.
With Pacific Coast Tick Fever exhibiting a summer trend so far, climate change and increasing temperatures have the potential to extend transmittal season in the Central Coast.
West Nile Virus, a mosquito-borne illness has also made a presence in the Monterey County, though to a much smaller extent than other parts of California. Rising temperatures, changing precipitation patterns, and a higher frequency of some extreme weather events associated with climate change will influence the distribution, abundance, and prevalence of infection in the mosquitoes that transmit West Nile virus and other pathogens by altering habitat availability and mosquito and viral reproduction rates. Alterations in the distribution, abundance, and infection rate of mosquitoes will influence human exposure to bites from infected mosquitoes, which is expected to alter risk for human disease.
The California Department of Public Health (CDPH) has also identified the Central Coast, and Monterey County as a high-risk area for Valley Fever. The illness, transmitted by the Coccidioides immitis fungus, is found in disturbed, dry soil particles that are breathed in. Its symptoms include chest pain, exhaustion, fever, coughing, joint and muscle pain, and difficulty breathing, among other symptoms, and can persist for weeks or even months. In particular, the 2006 Santa Barbara fires, driven to a great extent by high winds, may have exposed some 87 The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment, US Global Change Research Program (2016)
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firefighters to the illness while they engaged in soil disruption and removing vegetation to prevent wildfire spread.
Vector-borne pathogens are expected to emerge or reemerge due to the interactions of climate factors with many other drivers, such as changing land-use patterns. The impacts to human disease, however, will be limited by the adaptive capacity of human populations, such as vector control practices or personal protective measures.
19.5.9 SEVERE WEATHER
Climate change has already increased the number and strength of severe weather events and is likely to continue to increase in prolonged periods of excessively high temperatures, heat waves, extended frost, and severe winter storms. Extreme atmospheric river events, the dominant driver of locally extreme rainfall events and associated flooding, are expected to increase under projected climate change. Climate change impacts on other severe weather events such as thunderstorms and high winds are still not well understood.
19.5.10 SLOPE FAILURE
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.
The entire County will continue to be at risk for large, intense fires and thus as precipitation extremes increase, the probability also increases that an intense rain event will follow soon after a fire. Many areas of the County not previously in high landslide risk areas, may become increasingly at risk of post-fire debris flows due to increasing wildfire risk.
19.5.11 TSUNAMI
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.
19.5.12 WILDFIRE
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. Prediction of fire severity and frequency change in Monterey County is challenging Packet Page 539
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given the uncertainty in climate predictions of precipitation and wind for the region and the high and complex sensitivity of fire regimes in Mediterranean type Ecosystems to precipitation and climatic water deficits. It is important to recognize, however, that the basic characterization of this system as one that is dominated by fire is unlikely to change, and it is highly likely that that Monterey County will continue to see large, severe fires. Consequently, growing populations and expansion into the WUI will increase vulnerability to fires and projected increases in precipitation intensity during storms may increase post-fire impacts.
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.
19.6 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 County, 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 County. • Increased average temperatures along with changes in precipitation could affect groundwater supplies in the County
• 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 County. • A warmer climate will have an impact on the agriculture industry requiring research to better understand future impacts.
• Sea level rise has the potential to have major impacts on tourism industry.
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PART | C
C
PART C: MITIGATION CAPABILITY
AND STRATEGY
THIS PART DESCRIBES THE OVERALL CAPABILITY TO IMPLEMENT HAZARD
MITIGATION ACTIVITIES AND PROVIDES A VISION FOR FUTURE MITIGATION IN THE COUNTY. IT CONSISTS OF THE FOLLOWING SECTIONS:
20. CAPABILITY ASSESSMENT
21. MITIGATION STRATEGY
22. PLAN IMPLEMENTATION AND MAINTENANCE
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20. CAPABILITY ASSESSMENT
Thus far, the planning process has identified the hazards posing a threat to Monterey County and described, in general, the vulnerability of the County to these risks. The next step is to assess what loss prevention mechanisms are already in place, through the completion of a hazard mitigation Capability Assessment. The Capability Assessment helps determine the ability of a local jurisdiction to implement a comprehensive mitigation strategy, and to identify potential opportunities for establishing or enhancing specific mitigation policies, programs, or projects. As in any planning process, it is important to try to establish which goals and actions are feasible, based on an understanding of the organizational capacity of the agencies or departments tasked with their implementation.
The Capability Assessment is an important tool in determining which mitigation actions are practical and likely to be implemented over time based on a local government’s existing authorities, policies, programs, and resources available to support such implementation. The combination of the hazard Risk Assessment with the mitigation Capability Assessment results in the County’s net vulnerability to disasters, and more accurately focuses the goals, objectives, and proposed actions of this Plan. The Capability Assessment had three primary components:
1. An analysis of federal and state laws, ordinances, plans and programs that can support or impact hazard mitigation actions
2. An inventory of a jurisdiction’s plans, ordinances, programs, technical studies, or activities already in place and their relevancy to hazard mitigation
3. An analysis of a jurisdiction’s current capacity and resources to carry out relevant plans, ordinances, programs, or activities related to hazard mitigation Packet Page 545
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A careful examination of local capabilities will detect any existing gaps, shortfalls, or weaknesses associated with ongoing government activities that could hinder proposed mitigation activities and possibly even exacerbate hazard vulnerability. The Capability Assessment also highlights the positive mitigation measures already in place or being implemented at the local government level, which should be leveraged and continue to be supported and enhanced, if possible, through future mitigation efforts.
The Capability Assessment serves as a critical part of the planning process and helps identify and target meaningful mitigation actions for incorporation into the Mitigation Strategy. It helps establish both the countywide and jurisdiction-specific mitigation goals and ensures that those goals and the mitigation actions that follow are realistically achievable given current local conditions.
20.1 INCORPORATION OF EXISTING PLANS, STUDIES,
REPORTS, AND TECHNICAL INFORMATION
Existing laws, ordinances, plans and programs at the federal, state, and local level can support or impact hazard mitigation actions identified in this plan. Hazard mitigation plans are required to include a review and incorporation, if appropriate, of existing plans, studies, reports, and technical information as part of the planning process (44 CFR, Section 201.6(b)(3)). The following federal and state programs have been identified as programs that may interface with the actions identified in this plan. Each program enhances capabilities to implement mitigation actions or has a nexus with a mitigation action in this plan. Information presented in this section can be used in review local capabilities to implement the actions found in the jurisdictional annexes of Volume 2.
Each planning partner has individually reviewed existing local plans, studies, reports, and technical information in its jurisdictional annex. The Local process is described in Section 20.2 Local Capability Assessment and individual jurisdiction results are presented in Volume 2.
20.1.1 FEDERAL
Disaster Mitigation Act
The DMA is the current federal legislation addressing hazard mitigation planning. It emphasizes planning for disasters before they occur. It specifically addresses planning at the local level, requiring plans to be in place before Hazard Mitigation Assistance grant funds are available to communities. This plan is designed to meet the requirements of DMA, improving eligibility for future hazard mitigation funds.
National Incident Management System
The National Incident Management System (NIMS) is a systematic approach for government, nongovernmental organizations, and the private sector to work together to manage incidents involving hazards. The NIMS provides a flexible but standardized set of incident management Packet Page 546
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practices. Incidents typically begin and end locally, and they are managed at the lowest possible geographical, organizational, and jurisdictional level. In some cases, success depends on the involvement of multiple jurisdictions, levels of government, functional agencies, and emergency responder disciplines. These cases necessitate coordination across a spectrum of organizations.
Communities using NIMS follow a comprehensive national approach that improves the effectiveness of emergency management and response personnel across the full spectrum of potential hazards (including natural hazards, terrorist activities, and other human-caused disasters) regardless of size or complexity. Although participation is voluntary, Federal departments and agencies are required to make adoption of NIMS by local and state jurisdictions a condition to receive Federal Preparedness grants and awards.
Community Development Block Grant Disaster Resilience Program In response to disasters, Congress may appropriate additional funding for the US Department of Housing and Urban Development Community Development Block Grant programs to be distributed as Disaster Recovery grants (CDBG-DR). These grants can be used to rebuild affected areas and provide seed money to start the recovery process. CDBG-DR assistance may fund a broad range of recovery activities, helping communities that otherwise might not recover due to limited resources. CDBG-DR grants often supplement disaster programs of the Federal Emergency Management Agency, the Small Business Administration, and the US Army Corps.
Housing and Urban Development generally awards noncompetitive, nonrecurring CDBG-DR grants by a formula that considers disaster recovery needs unmet by other disaster assistance programs. CDGB-DR funding is a potential alternative source of funding for actions identified in this plan.
To be eligible for CDBG-DR funds, projects must meet the following criteria:
• Address a disaster-related impact (direct or indirect) in a presidentially declared county for the covered disaster
• Be a CDBG-eligible activity (according to regulations and waivers) • Meet a national objective. Incorporating preparedness and mitigation into these actions is encouraged, as the goal is to rebuild in ways that are safer and stronger.
Emergency Watershed Program
The USDA Natural Resources Conservation Service (NRCS) administers the Emergency Watershed Protection (EWP) Program, which responds to emergencies created by natural disasters. Eligibility for assistance is not dependent on a national emergency declaration. The program is designed to help people and conserve natural resources by relieving imminent hazards to life and property caused by floods, fires, windstorms, and other natural occurrences.
EWP is an emergency recovery program. This federal program could be a possible funding source for actions identified in this plan.
Financial and technical assistance are available for the following activities:
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• Removing debris from stream channels, road culverts, and bridges • Reshaping and protect eroded banks
• Correcting damaged drainage facilities
• Establishing cover on critically eroding lands
• Repairing levees and structures
• Repairing conservation practices
Emergency Relief for Federally Owned Roads Program
The US Forest Service’s Emergency Relief for Federally Owned Roads Program was established to assist federal agencies with repair or reconstruction of tribal transportation facilities, federal lands transportation facilities, and other federally owned roads that are open to public travel and have suffered serious damage by a natural disaster over a wide area or by a catastrophic failure. The program funds both emergency and permanent repairs. Eligible activities under this program meet some of the goals and objectives for this plan and the program is a possible funding source for actions identified in this plan.
National Flood Insurance Program
The National Flood Insurance Program (NFIP) provides federally backed flood insurance in exchange for communities enacting floodplain regulations. Participation and good standing under NFIP are prerequisites to grant funding eligibility under the Robert T. Stafford Act.
Monterey County and all of the municipal planning partners participate in the NFIP and have adopted regulations that meet the NFIP requirements. At the time of the preparation of this plan, all participating jurisdictions were in good standing with NFIP requirements. Full compliance and good standing under the NFIP are application prerequisites for all FEMA grant programs for which participating jurisdictions are eligible under this plan.
Presidential Executive Orders 11988 and 13690
Executive Order 11988 requires federal agencies to avoid to the extent possible the long and short-term adverse impacts associated with the occupancy and modification of floodplains and to avoid direct and indirect support of floodplain development wherever there is a practicable alternative. It requires federal agencies to provide leadership and take action to reduce the risk of flood loss, minimize the impact of floods on human safety, health, and welfare, and restore and preserve the natural and beneficial values of floodplains. The requirements apply to the following activities:
• Acquiring, managing, and disposing of federal lands and facilities • Providing federally undertaken, financed, or assisted construction and improvements • Conducting federal activities and programs affecting land use, including but not limited to water and related land resources planning, regulation, and licensing.
Executive Order 13690 expands Executive Order 11988 and acknowledges that the impacts of flooding are anticipated to increase over time due to the effects of climate change and other threats. It mandates a federal flood risk management standard to increase resilience against Packet Page 548
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flooding and help preserve the natural values of floodplains. This standard expands management of flood issues from the current base flood level to a higher vertical elevation and corresponding horizontal floodplain. The goal is to address current and future flood risk and ensure that projects funded with taxpayer dollars last as long as intended.
All actions identified in this plan will seek full compliance with all applicable presidential executive orders.
The Clean Water Act
The federal Clean Water Act (CWA) employs regulatory and non-regulatory tools to reduce direct pollutant discharges into waterways, finance municipal wastewater treatment facilities, and manage polluted runoff. These tools are employed to achieve the broader goal of restoring and maintaining the chemical, physical, and biological integrity of the nation’s surface waters so that they can support “the protection and propagation of fish, shellfish, and wildlife and recreation in and on the water.”
Evolution of CWA programs over the last decade has included a shift from a program-byprogram, source-by-source, and pollutant-by-pollutant approach to more holistic watershedbased strategies. Under the watershed approach, equal emphasis is placed on protecting healthy waters and restoring impaired ones. A full array of issues is addressed, not just those subject to CWA regulatory authority. Involvement of stakeholder groups in the development and implementation of strategies for achieving and maintaining water quality and other environmental goals is a hallmark of this approach.
The CWA is important to hazard mitigation in several ways. There are often permitting requirements for any construction within 200 feet of water of the United States, which may have implications for mitigation projects identified by a local jurisdiction. Additionally, CWA requirements apply to wetlands, which serve important functions related to preserving and protecting the natural and beneficial functions of floodplains and are linked with a community’s floodplain management program.