Floods & floodplain planning

We lead floodplain management in Washington by providing technical assistance and grants to local communities to help them better plan within a floodplain. We work to reduce life and property losses, and protect the environmental functions that floodplains offer.

Flooding is the state's most costly natural disaster

Cleaning up after a flood costs three times more than preventing flood damage in the first place. We help communities manage their floodplains by offering resources to identify flood hazards, plan a more flood-resilient landscape, and complete projects that reduce flood risk to both life and property.

In Washington, the costs of flooding exceed all other natural hazards. There is over an 80% chance that 10 or more flood events will happen on any given year in the state, and the frequency of events will increase as the climate changes. Several types of floods occur across the state's diverse geography. In Western Washington, floods typically result from prolonged winter rains. In Eastern Washington and in the Cascades, spring snowmelt and rain-on-snow events are the primary causes of flooding. Coastal storm surges, overwhelmed storm drains, flash floods, ice jam and debris blockages, and channel migration are also potential sources of damage.   

We help communities plan for, mitigate, and recover from flood damage. If you are in a flooding situation, your local government or 9-1-1 is your first contact.

Technical assistance and planning

Floodplain Management Program – As the state’s lead agency for flood risk reduction, we assist local governments with the National Flood Insurance Program and Washington floodplain management program. We provide technical assistance and training, planning and regulatory guidance, flood ordinance reviews, and community assistance visits to communities.

Critical Areas Ordinance & Frequently Flooded Areas – Washington cities and counties are required to periodically review and update their Critical Areas Ordinances (CAO). To promote safety from floods, frequently flooded areas are covered by the CAO. For more information, see Guidance for Floodplains: Critical Area Ordinance (CAO).

Office of Chehalis Basin – The Office of Chehalis Basin was established at Ecology in July 2017. We are working to carry out a collaborative effort to reduce flood damage and restore aquatic habitat in the Chehalis River basin.

Floodplain grants

Floodplains by Design is our primary grant program for floodplain projects. This partnership of local governments, state and federal agencies, and private organizations works to coordinate multi-benefit projects that reduce flood hazards and restore the natural functions of the floodplain.

The Flood Control Assistance Account Program is the main source of funds for floodplain management planning. Due to budget constraints, we can only provide emergency assistance grants at this time. We have created a document "Focus On: Planning for flood risks" detailing the need to restore legislative funding to help communities with their flood-risk reduction activities.

Risk MAP: Flood maps & more

We work in partnership with FEMA to run the Risk MAP program in Washington. This program delivers high-quality data, risk assessment tools, and mitigation expertise to local and tribal governments and communities to reduce risks from natural hazards, including floods, earthquakes, wildfires, and landslides.

Our RiskMAP app shows current Washington projects and effective flood hazard maps.

Fighting flood hazard risk together

Statewide, we assist FEMA, the Washington Military Department's Emergency Management Division, and partner with many others, including the U.S. Army Corps of Engineers Silver Jackets program to:

  • Evaluate community floodplain management programs and review ordinances.
  • Participate in statewide flood hazard mitigation planning and projects.
  • Assist with funding challenges through flood grants and technical assistance.
  • Coordinate in floodplain mapping.
  • Regulate Washington's flood hazard management statues and rules.

We have regional floodplain management staff in Spokane, Union Gap, Bellevue, and Olympia to assist communities. For more information, contact the floodplain specialist for your area listed below.

List of regional floodplain contacts.