Monterey County, California Multi-Jurisdictional Hazard Mitigation Plan

Monterey County, California and its twelve incorporated municipalities have integrated climate change into their combined Multi-Jurisdictional Hazard Mitigation Plan. Hazard Mitigation Plans guide state and local efforts to reduce disaster losses of life, property, and infrastructure, including transportation assets. Home to more than 400,000 people, Monterey County sits along the California coast, where it faces numerous climate-connected - often interrelated - threats, including sea-level rise, coastal erosion, flooding, wildfires, and landslides, which can all affect transportation. The plan identifies county-wide hazards and proposes general mitigation goals, as well as jurisdiction-specific hazard-mitigation recommendations are included in appendices to the Plan. 

The Plan assesses how climate change will affect the intensity and severity of impacts from natural hazards, including potential impacts to transportation assets. The Plan estimates that 5-feet of sea-level rise will directly place at risk more than six miles of highway, over eight miles of railroad, and six bridges, by 2100. In determining the rate of sea-level rise to use for planning, the county used projections developed by the state pursuant to California Exec. Order S-13-08. These projections were developed using IPCC and National Oceanic and Atmospheric Administration’s (NOAA) data, as well as data from California's Third Climate Change Assessment (2012). Coastal erosion will also be exacerbated by sea-level rise and more than 10 miles of county highways are located within the area projected to be affected by coastal erosion within 100 years. Although the plan only uses the historical 100-year floodplain to assess assets at risk of flooding, the Plan notes that changes in rainfall intensity and duration caused by climate change could affect future flood risk. Additionally, other climate-related hazards such as wildfires, can reduce the retentive capacity of soils, which can also exacerbate flooding. 

Based on the report’s review of infrastructure located within the 100-year floodplain, riverine and coastal flooding threatens more than 40 miles of highway, 15 miles of railroad tracks, and 80 bridges. Wildfires pose a moderate to very high threat to more than 215 miles of highway, more than 60 miles of railroad, more than 80 bridges, and a multitude of airports within Monterey County and its municipalities. Depending on different GHG emission scenarios, it is estimated that annual burn areas will increase by 19-28% by 2085. Wildfires also contribute to landslides, which have a direct impact on transportation networks and assets. Landslides already have plagued some areas of Monterey County, and are particularly problematic in Big Sur - where they have led to shutdowns of Highway 1 and threaten over 60 miles of highway, more than five miles of railroad, more than 20 bridges, and three airports.

To address these hazards, the Plan offers a number of countywide and jurisdiction-specific recommendations for reducing risks to transportation assets and systems:

  • To address sea-level rise, the Plan recommends prioritization of improvements to one road in particular: Elkhorn Road, which already floods during the largest annual tides and is expected to be inundated by projected sea-level rise. When flooded, emergency access to the area is barred.  Among the improvements the Plan recommends is to reduce obstacles to tidal flow as part of the effort to protect the road from flooding, improve water quality, and control erosion. (H-26).    
  • Although the Plan does not recommend specific actions for reducing threats from coastal erosion, it does note that shoreline protection such as groins, jetties, and seawalls can exacerbate the problem.
  • To address riverine and coastal flooding, the Plan recommends continuing to routinely update countywide flood inundation maps; carrying out planned riverine flood-control programs (such as efforts to install additional pumping capacity, flood walls, and expanded levees in the Lower Carmel River); and implementing planned watershed restoration programs to mitigate flooding and increase ecosystem capacity (such as restoration plans for the Salinas River). In some areas, the Plan recommends modifying culverts and storm drains and installing retention basins to protect transportation infrastructure.
  • To reduce the impact of wildfires, the Plan recommends the creation of fire breaks and fire-fuel management programs, controlled burns, public education, and special consideration of emergency evacuation routes when evaluating permits for new residential units. The Plan also recommends clearing vegetation that is not resistant to fires, as well as nonnative species, within 30 feet of access roads and evacuation routes.

The Plan also includes a range of general solutions for targeting all hazards, including: participating in federal community-preparedness programs such as Stormready and Fireready; providing for advisory radio and television spots; hosting informational websites; requiring real-estate disclosures for properties at risk to natural hazards; maintaining emergency-warning systems, providing emergency-response training, maintaining evacuation management plans; encouraging private-sector involvement in disaster planning; promoting school education campaigns and broad public dissemination of the Plan. The Plan also encourages municipalities to incorporate preparedness measures into their comprehensive plans, capital-improvement programs, and stormwater-management regulations.

To complete the hazard and vulnerability analyses, the County relied on a variety of government sources, including data from the Federal Emergency Management Agency (FEMA), the U.S. Geological Survey, the California Geologic Survey, and the National Weather Service.  Planners used GIS to map hazards and identify vulnerabilities and made use of data and tools available through the NOAA’s Digital Coast platform. The Plan, initiated in 2013-2014, was revised in June 2015 based on FEMA comments.  The County Board of Supervisors adopted the Plan by resolution in February 2016; the 12 participating municipalities will individually ratify it next.


This Adaptation Clearinghouse entry was prepared with support from the Federal Highway Administration. This entry was last updated on March 31, 2016.


Publication Date: June 2015


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