Flooding services and information
King County is updating its Flood Hazard Management Plan. Learn about the scope of the update, its schedule and how you can provide input.
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.
Road conditions and closures map
Look up roads that are closed from water over the roadway or flood damage from an interactive map of King County.
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.
Review the latest floodplain boundaries in King County and look up or order maps from various sources.
Flood related facts in King County as of 2012:
- There are approximately 8,000 parcels located in a King County floodplain;
- River flooding has led to 12 presidentially declared disasters in King County since 1990;
- Even though local flooding most commonly occurs between November and February, historically King County rivers have flooded in every month of the year except August;
- The leading cause of flood-related deaths is from motorists driving through standing water or around barricades or road-closure signs;
- Federal financial assistance is only available following a federal disaster declaration;
- Most homeowners insurance does not cover flood damage. Go to www.floodsmart.gov and fill out the red form, "How can I get covered?" to rate your flood risk, estimate premiums and find an agent.
Current capital projects to reduce flood hazards on King County rivers.
Flood protection - King County performance measures
This measure describes the flood hazard risks reduced through the King County flood protection program.
King County Flood Control District
Learn about the purpose, governance structure and schedule of activities for this recently established flood management district.
Community Rating System
Learn about a National Flood Insurance Program (NFIP) incentive program that encourages communities to accurately assess risks and reduce flood losses, and rewards better flood management with reduced insurance premiums for its residents.
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.
Interactive map - water-related sensitive areas
Note: this link will open a new browser window
Pick the King County map layers you want and click the "refresh map" button located at at the bottom of the layers list to display floodways, 100-year floodplains, channel migration hazard areas, parcels and other map-based information. Viewing information about individual map features may take some practice: choose the "active" (or queryable) map layer from the layers list, select the tool, and click on one of that layer's features to display associated data.
Interactive map - stormwater complaints, facilities, projects and studies
Note: this link will open a new browser window
Zoom in to view the full set of the County's map layers including drainage complaints, the regional, commercial and residential stormwater facilities, neighborhood drainage projects, stormwater studies, and aerial imagery among other things. Viewing information about individual map features may take some practice: choose the "active" (or queryable) map layer from the layers list, select the tool, and click on one of that layer's features to display associated data.
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.
City of Snoqualmie hazard mitigation planning (external link)
Find public process documents for an update to the city's 2003 multi-hazard mitigation plan including meeting agendas, minutes, and documents including some covering flood mitigation.
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.
Take Winter by Storm
Find breaking storm news and a directory of resources for Seattle-King County residents.
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.
Erosion control for construction sites
This page provides information for about how to prevent runoff at construction sites during the wet season, from the Dept of Development and Environmental Services.
Natural hazards: flooding
This page is published by the King County Office of Emergency Management. The page provides background information about flooding in King County, including background flooding information, history, vulnerabilities and effects.
2006 King County Flood Hazard Management Plan
The 2006 King County Flood Hazard Management Plan sets forth a ten-year strategy for how King County proposes to manage its rivers and floodplains to minimize flooding and channel migration hazards throughout the county. The 2006 Plan establishes policy, program and project recommendations to improve public health and safety, and to minimize risks to people, property, roads, public infrastructure, and natural resources. The 2006 Plan does not propose any changes to current flood hazard regulations.
The connection between floodplains and the economy
Learn about the economic effects of flooding on King County businesses and the region's overall economy.
South Fork Snoqualmie River Gravel Removal Study New!
Evaluates the effectiveness of gravel removal for reducing floods on the South Fork Snoqualmie River upstream of the North Bend Boulevard (Bendigo) Bridge.
Erosion and sediment control standards
Appendix D of the King County Surface Water Design Manual. 1 MB Adobe Acrobat file.
Snoqualmie flood-farm task force report
Provides finding 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 Climate Change Plan
How King County seeks 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.
» Other flooding-related documents
Other flood projects
Lake Allen Outlet Project
Culvert work to alleviate roadway flooding.
Lower White River countyline reach flood projects
Levee setback projects to increase flood storage and reduce the risk of flood damage during high-water.
Lower Tolt River Floodplain Restoration Project
Overview of a habitat restoration project designed to return the lower Tolt River to its historic meandering state and rich habitat diversity while continuing to provide flood protection and park uses.