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Learn what to do before, during and after a flood. Look up, locate, and order flood hazard maps. Print the page and keep it on hand just in case.

Flood warnings and alerts
Flood conditions, warnings and alerts for major rivers and streams in King County including Snoqualmie River, Tolt River, Skykomish River, Raging River, Issaquah Creek, Cedar River, Green River, and White River.

King County Road Alerts, road conditions and closures
Sign up for free Road Alerts, look up roads that are closed from water over the roadway or flood damage using this interactive map.

Report a water quality or drainage problem
Use the phone number or an online form to request an investigation into water quality and drainage problems in King County. This page also contains background information to help residents understand how problems are handled.

Floodplain mapping 
Review the latest floodplain boundaries in King County, look up or order maps from various sources and find out about Elevation Certificates.

Interactive map - flood information
Note: this link will open a new browser window
Zoom in to your area of interest. In the layers list, click "Flooding info" and the layers you need: FEMA preliminary 500-year or 100-year floodplain, FEMA preliminary floodway, flood photos, river gages or river facilities. Click on point symbols for photos and data.

Interactive map - stormwater information
Note: this link will open a new browser window 
In the layers list, click "Stormwater Services" and the layers you need: drainage complaints, surface water engineering projects, neighborhood drainage projects, drainage studies, surface water design manual or stormwater facilities.

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.