Thurston County Flood Hazard Mitigation Plan

Follow the plan's progress and other flood information on the Thurston County webpages:

 Flood Plans   Emergency Management Plans 

County staff are organizing a Flood Planning Committee for 2025. Committee members will include government and public stakeholders, and will meet approximately 5 times in 2025.

Meetings will be held every 4th Tuesday, January- May at 10am with a virtual attendance option for members and the public.

For more information on how to attend, please visit the  Flood Plans webpage  or email Amelia Schwartz at  Amelia.Schwartz@co.thurston.wa.us  .

To submit a comment to be reviewed by the Flood Plan Committee and county staff, please submit through the comment portal on the webpage:  Flood Plans 

Flooding in Thurston County is not only common, but is also the costliest natural hazard affecting residents, businesses, and the county government.

Zoom in on the map to see where flood hazards exist in Thurston County.

Floodplain: A strip of land next to a stream that's made of sediment and is prone to flooding.

100-Year Floodplain/Flood Zone: Land that has a 1 percent chance of flooding in a year.

500-Year Floodplain/Flood Zone: Land that has a 0.2 percent chance of flooding in a year.

Floodway: A river channel that takes the river water when it floods.

High Groundwater Hazard Areas: Area that floods because the soil type soaks up the water too slowly.

Flood Stage: The water level at which water has risen high enough to areas that are not normally covered by water. This is considered a flood event.

Special Flood Hazard Area (SFHA): The area where the National Flood Insurance Program (NFIP) enforces floodplain management regulations and where home and business owners must purchase flood insurance.

Flood Insurance: Often separate from home insurance, could be useful if your property is at risk of flooding. Flood insurance may be required in areas at high risk of flooding.

National Flood Insurance Program (NFIP): provides flood insurance to property owners, renters and businesses.

Community Rating System (CRS): a voluntary program that encourages community floodplain management practices that exceed the minimum requirements of the NFIP. Thurston County is one of the highest-classed communities in the nation.

Riverine (river and stream) flooding occurs when more water enters a river or stream than it can hold.

Groundwater flooding occurs when the soil type soaks up the water too slowly.

Tidal flooding occurs when high tides join with storm surge to flood areas.

Urban flooding occurs when runoff exceeds infrastructure's ability to divert water within suburban and urban areas.

Lake flooding occurs when lake levels rise past their maximum high water level.

Dam Failure occurs when a dam fails to hold the water behind a dam.

 Thurston County Community Alert System 

Sign up to receive free emergency alerts from Thurston County Alert System. TC Alert uses several types of alerts to warn the public of emergency and non-emergency incidents within Thurston County.

Current alert types include:

• Flooding
• Burn Bans
• Boil Notices