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Flood services and information

Flood services and information

King County, Washington

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.

Programs and projects

King County Flood Control District
Learn about the purpose, governance structure and schedule of activities for this flood management district, established in 2007.

Community Rating System
Learn about a National Flood Insurance Program (NFIP) incentive program, which encourages communities to accurately assess risks and reduce flood losses and rewards better flood management with reduced insurance premiums for its residents.

Farm Pad Program
Find help with building a farm pad to protect livestock in King County floodplains.

Flood Buyout and Home Elevation Program
This page answers frequently asked questions about King County's program to buy houses located in floodplains or provide homeowner assistance in having homes elevated. The page also provides information about related programs that can help homeowners affected by flooding.

Restoring Rainbow Bend: Good for People and Fish from King County DNRP on Vimeo.

Shoreline management
Learn about King County's program to protect shorelines, promote public access and establish priorities for shoreline uses along shorelines and flood areas of county's large rivers.

Hydrologic Information Center
This page provides local rain and stream gage data and flood reports for King County river basins, including the Cedar River, Snoqualmie River, Issaquah Creek, Bear Creek, and Green River Basins. The page provides current information about water levels as well as reports about flooding in years past.

Stormwater retention/detention (R/D) facilities
Learn why King County requires, maintains and inspects facilities that catch and slowly release stormwater that drains from our residential areas.

Combined Sewer Overflow (CSO) Control Program
Learn what King County is doing to eliminate the discharge of raw sewage that may result from stormwater exceeding the capacity of combined sewers, and read a map showing where such discharges may occur.


King County Flood Hazard Management Plan
Our guide for managing flood risks along our rivers, creeks, and shorelines. We’re in the process for creating a new flood plan by 2024.

Snoqualmie Flood-Farm Task Force Report
Provides findings and recommended mechanisms to help Snoqualmie Valley farms that get periodically flooded in ways that maintain good floodplain management and continue salmon recovery in the lower Snoqualmie River.

King County Strategic Climate Action Plan
How King County plans to reduce greenhouse gas emissions, adapt to projected climate change impacts and embed mitigation and adaptation into county policy decisions. The plan incorporates issues, goals and actions related to flooding.