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King County Flood Management Plan

King County Flood Management Plan

Creating a flood resilient future

Over the next two years King County will update its Flood Management Plan. The flood plan is our guide for managing flood risks along our rivers, creeks, and coastlines. How does reducing flood risks impact rivers that support wildlife and farming? Ensure safe roads and reliable infrastructure? How do we address the likelihood of bigger floods with the resources available? What matters most to you?

To create the next plan, King County is learning about the interests and goals of our communities most vulnerable to flooding. What we learn will help us equitably shape our programs and policies for years to come.

Join us, let’s create a plan for a flood resilient future in King County.

About this project

As our most common natural disaster, flooding is part of life in King County. The flood plan will set floodplain management policy for unincorporated King County and could inform flood management actions by cities, the King County Flood Control District, and other floodplain partners.

SR 202 near Fall City damaged by flooding in 2009.
People work to assess damage to State Route 202 caused by the flooding of the Snoqualmie River in 2009.

Why is King County updating the flood plan?

Rivers and streams are alive—they change over time. King County last updated the flood plan in 2013. Since then, nearly 10 seasons of flooding have changed how our rivers look and function. Our population has grown, and we’ve added more homes and businesses to the landscape. How we develop land, manage waste, accommodate traffic, grow food, and recreate affects our rivers and coastal areas.

How will this flood plan be different?

To create a flood resilient future, the plan must represent the diverse perspectives of our community. Due to a variety of factors, including unjust historical practices, some communities are more at risk of flooding. Some people are less able to prepare or recover from flood disasters. Understanding what all communities need and their proposed solutions is King County’s priority.

King County will work directly with communities on the flood plan in 2022 and 2023. Engagement opportunities will include community partnerships, advisory groups, and online surveys. King County will also hold open houses, and virtual meetings. Staff are available to join community-hosted meetings and share information.

Flooding along the coast of Vashon Island with blue houses on the right and Puget Sound on the left.
Coastal flooding on Vashon Island in 2021.

Past flood plans have focused on flooding along King County’s major rivers. This flood plan will capture a broader range of flood hazards that affect people. It will include coastal flood hazards and sea level rise, small stream flooding, and urban flooding.

The updated flood plan will look for ways that we can reduce flood risks while delivering other community benefits. How can our projects and programs support farming or create new jobs? Improve salmon habitat and provide recreational areas? What's most important to you and what does your community need?

Get involved

Sign up to receive flood plan updates and learn about ways to be involved in creating a flood resilient future. You can unsubscribe at any time.


Sign up for flood plan updates

Our core values in developing the flood plan are:

  • To stay community-centered.
  • Embrace transparency and openness.
  • Work with local partners.
  • Strive for full accessibility.
  • Have communities that are often left out of flood risk reduction conversations at the table.
Let’s plan ahead for flooding, together. We’re looking for your input to help everyone in our community be more resilient to flooding. Visit the 2024 King County Flood Management Plan engagement hub. You can share what flooding problems concern you in an online survey, open through June 30. You can also check out an upcoming events calendar or suggest events for King County to come to in your community.

Partner Planning Committee

The Partner Planning Committee is one avenue for gathering public input on the flood plan. Learn more about the purpose of the committee and upcoming committee meetings on the Partner Planning Committee webpage. 

State Environmental Policy Act process - environmental impact statement

An important part of our process to update the Flood Management Plan is to prepare an environmental impact statement (EIS). An EIS is a document that describes proposed actions and how they would affect the environment and people. Through the EIS process, King County will identify and analyze potential impacts of the plan on threatened or endangered species, water quality, historical and cultural resources, transportation, and more.

King County will explore the impacts of two scenarios, called “alternatives,” in the EIS. As a standard part of the EIS process, a “no action alternative” is considered. The analysis will consider the impacts of not adopting the new flood plan (the no action alternative) and continuing to use the 2006 and 2013 flood plans to guide floodplain management policy and activities and will also evaluate the impacts associated with adopting the new flood plan.

The County’s current flood plan focuses on flooding and erosion hazards on major rivers and streams like the Snoqualmie and Cedar rivers and Issaquah Creek. The updated flood plan proposes to address flooding more broadly on smaller streams and tributaries, lakes, and in urbans and coastal areas. Public comments from the EIS scoping period confirmed this broader scope has the potential to result in better outcomes for King County communities.

Learn more about the EIS process by reading our scoping fact sheet (1.11 MB, PDF).

Scoping period (completed in 2022)

The scoping period is a formal opportunity for public input. We invited the public, tribal governments, and local, state, and federal agencies to comment on the range of alternatives, areas of impact, and possible mitigation measures that should be evaluated within the EIS.

A 30-day comment period was held from Monday, Nov. 7 to Friday, Dec. 9, 2022. The submitted comments provided valuable information about topics to consider in evaluating potential environmental impacts. Many of these topics will be considered as the EIS is drafted. We also received comments that are not applicable to the EIS analysis but are relevant to the flood plan itself, and those comments will be considered as part of plan development.

Review the King County Flood Plan Environmental Impact Statement (EIS) Scoping Summary (May 2023), (PDF, 190 KB).

More opportunities to comment on the EIS

King County will offer another formal opportunity for public input during the draft EIS review period. This is when comments are requested on the merits of the alternatives and the adequacy of environmental analysis. Tentative timing is fall 2023.

Past flood plans

The most recent flood plan was completed in 2006 and adopted by King County Council in January 2007. The flood plan was last updated in 2013 and adopted by King County Council with the passage of Ordinance No. 2013-0419

Download the 2006 flood plan and 2013 flood plan update. These reports are provided in Adobe Acrobat .pdf format.

Printed copies of the 2006 flood plan and 2013 flood plan update are available at the following King County libraries:

  • Auburn Library
  • Bellevue Regional Library
  • Bothell Regional Library
  • Carnation Library
  • Duvall Library
  • Fairwood Library
  • Fall City Library
  • Issaquah Library
  • Kent Library
  • Maple Valley Library
  • Muckleshoot Library
  • North Bend Library
  • Redmond Regional Library
  • Skykomish Library
  • Snoqualmie Library
  • Tukwila Library
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