Community Planning - Floods

On September 30, 2025, the Thurston County Board of County Commissioners (BoCC) moved to adopt the 2025 Flood Hazard Mitigation Plan Update by resolution 16556.

County Flood Programs & Information

Floods are the most common natural hazard in Thurston County. Our average annual rainfall of 50 inches can lead to river, stream, and groundwater flooding. Many Thurston County departments provide programs and services to help community members keep themselves and their property safe. Find links to available information and programs below.

Emergency Alerts
Sign up to receive text or email alerts about hazardous conditions, including flooding. Thurston Community Alert (TC Alert) is Thurston County's primary alert and notification system for notifying community members of emergencies or hazards.

Thurston County Community Alert System
Visit the Emergency Management Alert and Notification website for more warning resources and information.
If you have a weather radio, you can access emergency alerts through frequency 162.475 MHz, Channel 4, or Thurston County SAME code 053067.
For more information about planning and preparing for emergencies, visit the Get Prepared! webpage.

Find Out If You're In A Flood Zone

Click the search icon.
Enter your address.
If your property is shaded a different color or pattern, view the legend on the left to match the hazard.

A Special Flood Hazard Area (SFHA) is defined as any A or V flood zone on a FEMA Flood Insurance Rate Map (FIRM). To visit FEMA's website and search for the map specific to your address, click here. You can also request assistance in finding your property's FIRM or existing elevation certificates by contacting the Building and Development Center at 360-786-5490 or permit@co.thurston.wa.us .

Flooding Links and Information

Existing Plans and Information:

The County regulates construction in flood hazard areas to protect residents and property from flooding. These standards also preserve floodplains as a natural means of flood control. Building responsibly and maintaining your drainage system can reduce your flood risks and prevent damage.

Prior to building, consider the following:

Homes vulnerable to floods must include flood protection when built.
There are restrictions on building new structures within the special flood hazard areas, including regulations on filling, tree-cutting, grading, and other development that may increase flood damage.
When requested, staff can visit your property to answer questions specific to your site, and discuss flooding, drainage, sewer backflow devices, and retrofitting. The County can also provide information on flood insurance, grants, loans, and other programs offered by federal, state, and local governments. Call or email the Thurston County Building Development Center for more information at 360-754-3355 ext. 6299 or planning@co.thurston.wa.us.

The Emergency Management department can help you prepare for flood season.

For more information about potential flood risks for specific river areas, visit the webpages below. Call Emergency Management at 360-867-2800 if you need assistance.

Nisqually River: The National Weather Service (NWS) issues a flood warning when water levels could potentially reach 10 feet or higher.
Skookumchuck River: NWS issues a flood warning when water levels could potentially reach 211.5 feet or higher.
Chehalis River: The NWS issues a flood warning when water levels could reach 141 feet or higher.
Deschutes River: The NWS issues a flood warning when water levels could potentially reach 11 feet. The Deschutes River rises and falls at a faster rate than any other Thurston County River.

Thurston County residents are eligible for up to 40% off of flood insurance! Standard homeowners and renters insurance policies do not include flood protection. Flood insurance policies can also be used for farms and commercial buildings.

Thurston County government is active in the Federal Emergency Management Act (FEMA) Community Rating System (CRS), which means you may be eligible for a discount through the National Flood Insurance Program (NFIP). Be proactive and buy flood insurance before you need it - there is typically a 30-day waiting period for an NFIP policy to go into effect.

Use the county's online Property Maps or the map above to see if your property is in a flood area. If not in a flood area, you may still be eligible for discounted flood insurance.
Contact an insurance agent for a quote, and let them know the county has a Class 2 CRS Rating.
- See flood insurance discount info in FEMA's Discount Explanation Guide and CRS Discount FAQ sheet .
- Learn about NFIP (National Flood Insurance Program) which is available through most insurance carriers. Note, NFIP offers coverage even if you're in a floodplain, or if your property has flooded before.
Learn more about NFIP on FEMA's website www.floodsmart.gov,
Learn more about the Community Rating System on the program website.
Learn More About the National Flood Insurance Program at www.floodsmart.gov

Thurston County is rated a Class 2 in FEMA's National Flood Insurance (NFIP) Community Rating System because the County's flood planning, flood reduction and flood education efforts exceed FEMA's minimum requirements. This rating provides up to a 40% discount on NFIP premiums within Thurston County.

Pursuant to the Flood Disaster Protection Act of 1973 and the National Flood Insurance Reform Act of 1994, the purchase of flood insurance is mandatory for all federal or federally related financial assistance (such as loans or mortgages) for the acquisition and/or construction of buildings in Special Flood Hazard Areas (SFHAs). An SFHA is defined as any A or V flood zone on a FEMA Flood Insurance Rate Map (FIRM). To visit FEMA's website and search for the map specific to your address, click here.

For National Flood Insurance Information, including a list of providers, contact the FEMA Mapping and Insurance eXchange (FMIX) center at (877) 336-2627 or by email. or visit floodsmart.gov. For Washington FEMA-related questions, contact FEMA Region X (10) at 425-487-4600, FEMA-R10-Info@fema.dhs.gov, or by visiting the Region 10 website. For information on support to pay the costs of bringing a home or business into compliance with local flooding regulations, visit the FEMA Increase Cost of Compliance webpage.

Use a County map to see if a Thurston County property address or parcel is within a mapped flood hazard area. Our staff work hard to make great maps, but they do not meet engineering, legal or survey standards. Consult with experts before making decisions.

County Flood Codes and Permit Information
Thurston County GeoData: Research the flood risk in specific areas or parcels.
FEMA Flood Maps and Floodsmart.gov: Research additional flood maps and information about flooding in your area.
Thurston County Flood Hazard Map: Use this to directly see most flood zones, waterbodies, and high groundwater areas in Thurston County.

For more information about a specific property or project, call or email the Thurston County Building Development Center for more information at 360-754-3355 ext. 6299 or planning@co.thurston.wa.us.

Find information on flood-related health issues, clean-up guidelines, water purification and food safety in the links below.

County staff monitor rainfall and water levels throughout the County. Check current water levels for Thurston County rivers and lakes by going to a site below.

To find out up to date information on road closures or to report a road hazard issue, please go to the link below.

Travel Impacts and Concerns in Thurston County

Travel Impacts Preparation:

Turn around, don't drown! Do not drive in or enter flooded areas, and do not drive around road barriers.
Create a travel preparedness plan, including a go-kit and travel plan for your family, including pets and farm animals.

The County's Public Works Water Resources Division actively manages the County's system of storm drains, pipes and ponds (also called stormwater facilities) making sure they move millions of gallons of rainwater runoff away from County homes and roads. Learn how to find and properly prepare your neighborhood stormwater facilities for the rainy season.

Thurston County Public Works conducts routine stormwater pond inspections and offers technical advice and assistance. Visit http://thurstonstormwater.org/, email stormwater@co.thurston.wa.us, or call 360-867-2095 for more information on stormwater facilities.

Don't drive or enter flooded areas. Flood waters can be deeper and faster than they appear. Hazardous materials and pollution can also be carried by flood waters.

Types of Flooding in Thurston County: Rivers, lakes, coastlines, and other sources can independently cause flooding. They often combine with above-normal rainfall to make floods more severe.

River and Stream Flooding occurs when more water enters a river or stream than it can hold. Frozen ground, or high tides and wind can also slow water movement in rivers, causing it to back up.

Groundwater Flooding happens when the soil type soaks up the water too slowly, and the groundwater is elevated with saturated soils.

Tidal (Coastline) Flooding occurs when high tides join with storm surge to flood areas along coastlines.

Urban Flooding happens when runoff from roads and other hard surfaces exceeds infrastructure's ability to divert water within suburban and urban areas. Increased development can reduce the amount of rain an area can absorb, and runoff increases.

Lake Flooding occurs when lake levels rise past their maximum high water level and more water goes into the lake than goes out.

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

Natural Floodplain Functions:

Floodplains can be community assets, and improve the quality of life for residents and visitors. Floodplains provide many benefits to the environment, including reducing flood impacts such as sedimentation and erosion, and even slowing flood speeds and heights. Floodplains also help to trap pollutants and clean dirty water by slowing floodwater and water runoff, allowing plants and soil to filter the water. Healthy floodplains also support plant growth, biodiversity, and ecosystems, providing more opportunities for farming, recreational opportunities, and scientific knowledge.

To support natural floodplain functions:

Don't clear or build in a floodplain.
Plant native trees and vegetations along streams and rivers.
Do not dump anything in storm drains, ditches, or waterways.