San Diego County Multi-Jurisdictional Hazard Mitigation Plan 2017

San Diego County, California updated its local hazard mitigation plan in 2017 to include climate change as an "emerging hazard." Climate change is not treated as a focal hazard in and of itself in San Diego County’s plan, but as a contributing factor that could affect the location, extent, probability, and magnitude of other hazards. This risk assessment considers climate change as a threat multiplier for extreme heat, coastal storms/erosion, wildfire, flooding, and drought/water supply.

A Risk Assessment was conducted for the county in which hazards were profiled by determining physical characteristics such as their magnitude, duration, past occurrences and probability. Base maps of the study area were created with hazard event profile information mapped. Then the assets in each jurisdiction were identified that will be affected by each hazard type. Assets include the built environment, people, economic factors, future development and the natural environment. The risk analysis process entailed evaluating vulnerable assets, describing potential impacts and estimating losses for each hazard - which is detailed further in the report.

The Plan’s Hazard Profiles provide a review of the hazard occurrence in the past, likelihood and risk in the future, and maps of projections. Hazard Profiles are included for: Climate Change; Sea Level Rise, Coastal Storms, Erosion and Tsunami; Dam Failure; Earthquake; Flood; Rain-Induced Landslide; Liquefaction; Structure/Wildfire Fire; Extreme Heat; Drought/Water Supply; and Manmade Hazards (technological hazards such as hazardous materials and terrorism).


Extreme heat is described as exacerbated by the urban heat island effect, which will have greater health impacts on vulnerable populations. San Diego County is said to have some of the highest percentages of impervious surfaces in the states, and extreme heat events “highlight the importance of thoughtful social vulnerability analysis.” 

Vulnerable populations discussed include the elderly, children, chronically ill, and people who work outside. People who live in urban areas with high impervious surface coverage and no access to air conditioning are also considered especially vulnerable. 

San Diego County’s plan includes an Objective to: Protect vulnerable populations from the effects of extreme heat. Actions indicated for this objective are to:

  • Support regional efforts to prepare for excessive heat events
  • Participate in “Excessive Heat Emergency Awareness” events and exercise heat emergency plans as established by HHSA, AIS, EMS, and PHS
  • Continue to provide “Cool Zones” during excessive heat events


Sea Level Rise, Coastal Storms, Erosion and Tsunami hazards were mapped and profiled as a group because many of the factors and risks involved are similar and limited to the coastal areas. Data used for these hazards included the digitized flood zones from the FEMA FIRM Flood maps, NOAA historical shoreline data, and Caltrans’ coastal zone boundary for the coastal storm/erosion hazard. Up to two feet of sea level rise is projected for the region by 2050, and low-lying areas could become inundated more frequently and with increasingly higher water levels. Particularly vulnerable communities to sea level rise include Imperial Beach, Coronado, Mission Beach, and parts of La Jolla Shores, Del Mar, and Oceanside.

Wildfire is currently a very high threat to property, lives, and ecosystems in the San Diego region. With projected higher temperatures and reduced rainfall, wildfire is likely to increase in the frequency and intensity.

Drought risk and Water supply are considered more impacted by climate change. Projections of further warming will result in reduced snowpack, and in turn reduced water supply for the San Diego region’s cities, agriculture, and ecosystems. Studies found that San Diego’s sources of water could be reduced by 20% or more by 2050. The report notes that at the same time that the San Diego region’s water supply is likely to decrease, water demand is expected to increase approximately 29% by 2050 due to economic growth and population pressures.

Potential exposure to every hazard was identified for each jurisdiction in San Diego County. Flooding was analyzed and charted for Potential Exposure and Losses from 100-Year and 500-Year Flood Hazard by Jurisdiction, as well as Potential Exposure to Critical Facilities and Infrastructure from 100-Year and 500-Year Flood Hazard by Jurisdiction.

Section 5 of the Plan includes a profile for each of the 21 participating jurisdictions, that describe unique:

  • mitigation goals and objectives
  • mitigation actions and priorities
  • an implementation plan, and
  • documentation of the mitigation planning process.

Participating Jurisdictions of this Hazard Mitigation Plan include: Carlsbad, Chula Vista , Coronado, Del Mar, El Cajon, Encinitas, Escondido, Imperial Beach, La Mesa, Lemon Grove, National City, Oceanside, Poway, San Diego, San Marcos, Santee, Solana Beach, Vista, County of San Diego, Alpine and Rancho Santa Fe Fire Protection Districts, Padre Dam Municipal Water District.


States and communities must have an approved mitigation plan in place in order to receive post-disaster Hazard Mitigation Grant Program federal funds. FEMA’s requirements for local hazard mitigation plans and planning process include the directive to ultimately create a “safe and resilient community.”


Publication Date: October 2017

Related Organizations:

  • San Diego County, California


Resource Category:

Resource Types:

  • Plans (other)

States Affected:


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