Floodplain maps

As part of the Federal Emergency Management Agency (FEMA) national Map Modernization Program initiative, FEMA has produced Preliminary Digital Flood Insurance Rate Maps (DFIRMs) and the corresponding Flood Insurance Study (FIS) for both the incorporated and unincorporated areas of King County. The most current revision of these Preliminary DFIRMs and FIS, dated November 6, 2010, show proposed special flood hazard areas that are subject to inundation by the base flood (100-year flood) as well the regulatory floodway.

Preliminary digital Flood Insurance Rate Maps and Flood Insurance Study

Vashon-Maury Island coastal flood hazard mapping

A public meeting was held on April 28, from 6 to 8 p.m. at the Vashon Island High School Commons.
(Open invitation in PDF, 56KB)
View the King County public meeting presentation and FEMA presentation to learn more.

The River and Floodplain Management Section has prepared a new coastal flood hazard analysis of the shoreline of Vashon-Maury Island. The new analysis was prepared in accordance with Federal Emergency Management Agency (FEMA) requirements and will be used to revise the flood insurance rate maps (FIRMs) and study (FIS) of the coastal shore of the islands. King County hosted a public meeting to present the draft study and maps to residents and provide information about the analysis.  FEMA representatives provided an overview of the federal mapping process and flood insurance.

Sammamish River

The River and Floodplain Management Section has provided new floodplain analysis of the Sammamish River to the Federal Emergency Management Agency (FEMA) for the purpose of revising the flood insurance rate maps (FIRMs) and study (FIS) for the Sammamish River extending from Lake Washington to Lake Sammamish. King County staff coordinated the new flood study with the cities of Kenmore, Bothell, Woodinville and Redmond), the State Department of Ecology and FEMA. It is expected that FEMA will conduct its quality assurance review of the new study during the fall of 2011.

White River

The work maps (linked below) show the areas from the King-Pierce County line to Stuck River Drive and from SR410 to Mud Mountain Dam.

Public Meeting for the near Enumclaw White River Flood Study October 22, 2008 6:30 pm Held at King County Fire District #28 1330 Wells Street, Enumclaw. View the public meeting presentation to learn more.

Presentation to Pacific City Council April 20, 2009. View the public meeting presentation to learn more.

Lower Snoqualmie River and Patterson Creek work maps

The work maps (linked below) were submitted to FEMA and included in the Preliminary Digital Flood Insurance Rate Maps.

*Lower Snoqualmie River Sheets 1-4 are Snohomish County floodplain work maps.

Lower and Middle Green River work maps

New flood boundary maps have been prepared for the Green River between the Duwamish Waterway in Seattle to Flaming Geyser State Park. The information was submitted to the Federal Emergency Management Agency (FEMA) on March 18, 2008 for the purpose of revising flood insurance rate maps. FEMA's technical review of the work maps was recently completed in 2010. The reviewed maps have some slight illustrative revisions as compared to the 2008 draft maps. Please note that no technical changes were made to the flood study analyses. The final-reviewed work maps are linked below.

Flood insurance and FEMA (Acrobat PDF format)
This bulletin explains the effect of the Federal Emergency Management Agency (FEMA) on the permitting process of the Department of Development and Environmental Services (DDES) and answers some common questions about the National Flood Insurance Program's (NFIP's) impact on development projects.

King County Code >> Critical Areas (Acrobat PDF format)
County definitions and rules on development standards, restrictions, and requirements as well as permitted uses in King County floodplains and other sensitive areas. Codes pertaining specifically to floodplains can be found under sections 21A.24.230 to 21A.24.275 of this document.

Flood map information for realtors, lenders and insurance agents

Online Floodplain Boundary Maps iMAP (high speed Internet connection required)
View and print custom online maps using King County data including parcels, floodway and floodplain boundaries.

FEMA flood hazard maps (external link)
Information on locating Flood Insurance Rate Maps (FIRM), understand how to read them, and requesting a map change.

FEMA flood map store, Online Map Viewer (external link)
Order or view current Flood Insurance Rate Maps online.
(registration required, no charge to view maps)

For questions about the floodplain mapping, please contact Ken Zweig, River and Floodplain Management Section.