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The King County Regional Hazard Mitigation Plan will be undergoing its five-year 2020 update between now and December 2019. The update reassesses risks and vulnerabilities to nine natural and seven human-caused hazards, and develops strategies to reduce risk to those hazards. Each of nearly 60 planning partners will develop an annex to the plan, including the risk-reduction strategies that are a key output of the plan. The plan is also a requirement for receiving federal Hazard Mitigation Assistance grants.

Your input in this planning process will be used to prioritize hazard mitigation investments by helping us identify and weigh critical values. Want to get involved, or have questions? Please contact Derrick Hiebert, Hazard Mitigation Strategist at

What is hazard mitigation?

Hazard mitigation is another word for disaster risk reduction. It is focused on actions with long-term benefits and can include projects that reduce risk or development codes that prevent it. Hazard mitigation plans are developed periodically by states, counties, and cities to assess risks and identify actions to address those risks.

According to research from the National Institute of Building Sciences, hazard mitigation saves, on average, $6 for every $1 spent. Accordingly, communities throughout King County are investing in projects to increase disaster resilience. Hazard mitigation projects take several forms, including:

  • Strengthen an asset. Seismic retrofits of earthquake-prone buildings or infrastructure are examples of this.
  • Move an asset. Buyouts of flood-prone property to save taxpayers on future insurance payouts are examples of this.
  • Prevent or regulate the development of new assets in hazard-prone areas. An example of this is your local building code or development guidance that regulates construction on steep slopes.

Each of these "styles" of hazard mitigation can be applied to any hazard we face. See below for some of our most serious hazard threats and strategies we may use to reduce risks to our communities. View a complete list of all the hazards assessed through this plan update.

Flood Hazard Annex

A small committee of County staff and stakeholders will help craft the flood portion for the King County annex. The public is welcome to attend any of the meetings:

  • Oct. 30, 2019 from 10 a.m. – noon. Focus: Developing mitigation strategies
  • Nov. 6, 2019 from 10 – 11 a.m. Focus: Implementation and review of the final draft

An earlier meeting focused on risk assessment.

Meetings will be held at:

City of Snoqualmie
38624 SE River Street
Snoqualmie, WA

For specific room information or to submit comments, email Mitch Paine.

Effective hazard mitigation

The hazard

  • Earthquake is the potentially most damaging hazard affecting the county, with devastating regional impacts.
  • A major Cascadia Subduction Zone or Seattle Fault event would cause tens of billions of dollars in damages, hundreds of fatalities, and destroy regional transportation, communications, and utility networks.
  • Current building standards distinguish between life safety codes and immediate occupancy codes. Life safety implies that the building will not collapse but may not be habitable. Immediate occupancy facilities are designed for use immediately after an incident. Most buildings are constructed to life safety standards.
  • A major risk in King County is from unreinforced masonry structures exemplified by the historic, brick-façade buildings in Pioneer Square. Older buildings are generally most at risk, having been built to lower standards.
  • Smaller, deep earthquakes occur approximately every 50 years, most recently in 2001 with the Nisqually Earthquake, and massive subduction zone earthquakes occur every 300-500 years, most recently in 1700.
  • Areas with saturated soils, land made by filling in a waterbody, and soils of certain classes can be highly susceptible to liquefaction. This includes low-lying areas like river valleys and the land on which Pioneer Square and the Port of Seattle are built.
  • More information on geologic risk in Washington.

Effective mitigation

  • Preventing or reducing earthquake damage requires sustained investment in resilient buildings and infrastructure over decades. Appropriate building standards supplemented by a retrofit program for existing structures is the most cost-effective way to reduce risk.
  • Structural retrofits to buildings and infrastructure to higher seismic standards can save lives and property and dramatically speed post-disaster recovery.
  • Warning systems, such as Earthquake Early Warning, can reduce damage and save lives by providing seconds to drop, cover, and hold on and for water or power systems to temporarily shut down.
  • King County, Washington State, and other local governments invest in seismic retrofits to public facilities, including buildings, bridges, roads, utility systems, and other essential services.

The hazard

  • Floods can be caused by rapid snow melt or major rain events. Most of the funding for risk reduction projects in Washington is for flood hazards.
  • The rivers in the south and east of King County are the highest risk areas, such as along the Green, the Cedar, and the Snoqualmie Rivers. Communities in these areas can sometimes be cut off for days by floodwaters.
  • The last time floodplain maps were adopted was in the 1980s. A new set of floodplain maps are in review now.
  • Climate change is expected to increase the frequency and severity of precipitation events in our region, which may change the floodplain even more and result in many more disasters.
  • More information on flooding in King County.

Effective mitigation

  • Property elevations and acquisitions can remove homes from the floodplain.
  • Drainage projects reduce the risk to flooding caused by runoff.
  • Major ecosystem restorations can have benefits of reducing flood risk and creating new open space that is beneficial to salmon and other wildlife. Levee setbacks are one of the most common projects that do this.
  • Removing impediments to flood waters, such as undersized culverts, can lower upstream floodplains, while also improving fish passage.
  • Washington State has some of the most effective floodplain regulations in the country, and King County is one of only 7 communities, and one of only three counties – all in Washington, receiving a “Class 2” rating from the Community Rating System in recognition of flood hazard mitigation and strong development regulations.

The hazard

  • Landslides are ubiquitous to Washington and can occur in any steep slope area.
  • Extreme winter events can produce hundreds to thousands of landslides in Western Washington in a single series of events.
  • King County and WA DNR recently completed an updated landslide inventory for the county.
  • More information on geologic risk in Washington.

Effective mitigation

  • Slope stabilization measures, such as retaining walls or drainage improvements can reduce the risk of slope failure.
  • Homes can be built on pylons or foundations to reduce susceptibility to slope failure and pressure on the slope from the weight of the house.
  • The Critical Areas Ordinance requires any new construction in landslide-prone areas to build-in mitigation measures.

The hazard

  • Severe weather, along with flood, is the most common disaster in our region and is the source of most federal disaster declarations.
  • The largest sources of damage are utilities and transportation infrastructure.

Effective mitigation

  • Measures that protect utility infrastructure are the most common severe weather mitigation strategies in King County. Examples include underground power lines and installing backup generators at critical facilities.

The hazard

  • Known tsunami risk is relatively limited in King County, concentrated along Puget Sound, especially around the Port of Seattle
  • In Washington as a whole, this is potentially the deadliest hazard.
  • More information on geologic risk in Washington.

Effective mitigation

  • Tsunami “safe havens” – buildings designed to withstand tsunami waves as evacuation structures
  • Warning networks, including sirens, text alerts, and public information campaigns

The hazard

  • Lahars from an eruption to Mount Rainier would threaten south King County, around the communities of Auburn, Algona, Pacific, and Enumclaw.
  • A major eruption and lahar would also damage regional transportation networks.
  • Ash would cause damage around the region and trigger significant health impacts.
  • The 1980 Mount St. Helens eruption is one of the costliest disasters in Washington State history in lives and property.
  • More information on geologic risk in Washington.

Effective mitigation

The only effective mitigation to lahar impacts is to avoid risk through development standards and to prepare through information campaigns and the establishment of warning systems and evacuation routes.

The hazard

  • Wildland fire risk is changing in King County due to climate change – the “return period” for fire will be much lower and fires will be more frequent.
  • Development in the wildland urban interface – areas in which structures are adjacent or among heavy vegetation – is creating new risk in the county.
  • Building codes are still catching up as communities work to assess their risk.
  • Wildfire risk is most concentrated in the south and west of the county, where there are newer communities and more vegetated areas.
  • After a fire the risk continues in the form of dangerous flash floods and mudslides as rain on recently-burned “hydrophobic” soils runs into area waterways and down steep slopes.
  • More information on wildfire and how to live with it.

Effective mitigation

  • Building codes and development standards to require use of inflammable construction materials and more space in between homes can protect structures and prevent the spread of fire.
  • Neighborhoods designed for easy fire truck ingress and egress, by multiple routes are necessary to fight the fire and avoid tragedies like the Oakland Hills Fire in California.
  • Defensible space – clearing 30 – 100 feet around a home or neighborhood is the best course of action for existing communities.
  • Forest thinning and other forest-health measures can prevent some ignitions and help keep fires smaller.

The following King County jurisdictions, tribes, and special purpose districts are involved in our regional plan:

  • Auburn
  • Beaux Arts
  • Bellevue
  • Black Diamond
  • Bothell
  • Burien
  • Carnation
  • Clyde Hill
  • Coal Creek Utility District
  • Covington
  • Des Moines
  • Duvall
  • Enumclaw
  • Evergreen Health
  • Federal Way
  • Highline Water District
  • Hunts Point
  • Issaquah
  • Kenmore
  • Kent
  • King County Flood Control District
  • King County Water District 20
  • King County Water District 90
  • King County Water District 125
  • Kirkland
  • Lake Forest Park
  • Lake Meridian Water District
  • Maple Valley
  • Medina
  • Mercer Island
  • Midway Sewer District
  • Muckleshoot Tribe
  • Newcastle
  • Normandy Park
  • North Bend
  • North City Water District
  • Northeast Sammamish Sewer and Water District
  • Pacific
  • Puget Sound Regional Fire Authority
  • Redmond
  • Renton
  • Riverview School District
  • Ronald Wastewater District
  • Sammamish
  • Sammamish Plateau Water and Sewer District
  • SeaTac
  • Shoreline
  • Syway Water and Sewer
  • Snoqualmie
  • Snoqualmie Tribe
  • Soos Creek Water and Sewer District
  • Southwest Suburban Sewer District
  • Tukwila
  • Vashon Island
  • Woodinville
  • Woodinville Water District

The key deliverable of a successful planning process is a prioritized list of risk reduction strategies. These strategies are identified by each participating jurisdiction through an asset-based process that asks a series of questions:

  1. What makes your community great? What are the assets, features, factors, that you cannot live without? These can be both physical assets like fire stations, community assets like the business district, and intangible assets like the peace and tranquility of the community.
  2. What hazards potentially threaten those assets and values?
  3. What assets and values are susceptible, or vulnerable, to hazards?
  4. What happens if you lose those assets? What is the impact on your community? What is the impact from the asset’s failure or loss?
  5. Are these assets redundant? Can I afford to live without it?
  6. What can I do to reduce or eliminate the risk to this asset from hazards?

These are your mitigation strategies. Essentially, if you have an asset that is vulnerable and you cannot afford to lose it, then you must come up with some kind of strategy to reduce risk. Considerations:

  • What is the hazard?
  • What assets or values are at risk from that hazard?
  • What is the risk to those assets/values?
  • What other assets rely on that asset?
  • What effect does the loss of that asset have on my community or organization?
  • What effect does the loss of that asset have on other communities or organizations?
  • What can I do to reduce or eliminate the risk to that asset from this hazard?

Once the highly-vulnerable, highly-critical assets are identified, each community develops hazard mitigation strategic action plans to address the risk. These strategies are then prioritized by scoring the following elements:

Equity, Social Justice, and Vulnerability
Project is designed to benefit, account for, and include vulnerable populations, especially those in the community most likely to suffer harm from a disaster and those likely to take longest to recover after a disaster.

Project is supported by multiple jurisdictions or agencies.

Project has benefits beyond hazard risk reduction, including environmental, social, or economic benefits.

Adaptation and Sustainability
Project helps people, property, and the environment become more resilient to the effects of climate change, regional growth, and development.

Project is designed to attain the best-possible benefit-cost ratio.

Project is urgently needed to reduce risk to lives and property.

Project is largely ready to go, with few remaining roadblocks that could derail it.


  • -4 = Project actively harms or is detrimental to this factor.
  • 0 = Unsatisfactory for this factor
  • 1 = Minimal level of standards for this factor
  • 2 = Satisfactory level of standards for this factor
  • 3 = High level of standards for this factor
  • 4 = Outstanding or beyond expectations for this factor.

  • 2014 public meetings (presentation)
  • Plan and process overview (King County Council)
  • Community outreach (2013 Public forum)
  • July 2014 public meetings (presentation)
  • Plan and process overview (King County Council)
  • Community outreach (2013 Public forum)
  • Representatives from King County and 55 different cities, schools, fire districts, hospitals and utility districts worked in partnership with KCEM and Tetra Tech Incorporated - the contractor leading the hazard assessment and plan development. Decisions regarding plan elements, such as specific hazards to include, were made by a steering committee whose members include representatives from government, private business, non-profits, the public, and academia. 

    In 2015, the final updated plan was approved by Washington State EMD and FEMA. King County and most partnering jurisdictions have formally adopted their plans. The original RHMP is divided into seven sections:

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