Seattle, WA Environmental Rules: Flood Zones (2026)
FEMA flood zone rules in Seattle, WA, also called floodplain regulations or special flood hazard area (SFHA) rules, determine flood insurance requirements and elevation standards for new construction.
Key Facts
- Governing chapter
- SMC Chapter 25.06, Floodplain Development Regulations
- Administering agency
- SDCI citywide; SDOT in public right-of-way
- Map source
- King County FIRM dated August 19, 2020
- Civil penalty
- $500 per day until compliance (SMC 25.06.140)
- Application requires
- Elevation certificate from a licensed surveyor
Summary
Seattle requires a floodplain development permit before any construction, fill, or substantial improvement in FEMA-mapped special flood hazard areas, per Seattle Municipal Code Chapter 25.06. SDCI administers approvals citywide; SDOT handles work in the public right-of-way. Violators face a cumulative civil penalty of $500 per day until compliance is achieved.
Construction or development including the placement of or substantial improvement to manufactured homes and recreational vehicles not ready for highway use, shall not be undertaken within any special flood hazard area and flood-prone areas as defined in subsection 25.09.012.B as established in Section 25.06.050 without approval under this Chapter 25.06. For development where no other permit or authorization from The City of Seattle or its departments or agencies is necessary to begin or to accomplish the work, the approval shall be documented by issuance of a floodplain development permit or approval. For development where some other permit or authorization from The City of Seattle or its departments or agencies is required to begin or accomplish the work, including but not limited to development performed by City departments, the floodplain development approval shall be incorporated in such other permit or authorization.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Municipal Code: Supplement 44 Update 1).
Full Breakdown
050, Seattle's special flood hazard areas are identified using the FEMA Flood Insurance Study and Flood Insurance Rate Maps for King County dated August 19, 2020, plus the City's own flood-prone area maps; SDCI interprets unclear boundaries from actual field conditions or a FEMA Letter of Map Change. 060 then bars construction or development, including placement of or substantial improvement to manufactured homes and highway-unready recreational vehicles, in those areas without a floodplain development approval: issued as a standalone permit or folded into another required permit.
070 requires the application to include a licensed surveyor's elevation certificate referenced to NAVD 88, a floodproofing certification from a registered engineer or architect for nonresidential structures, a V-zone design certificate for VE-zone work, and a no-rise engineering analysis for floodway development. 080 splits administration: the SDCI Director handles approvals citywide, while the SDOT Director administers work within the public right-of-way. 090 directs the administrators to confirm the site is reasonably safe from flooding, verify the proposal isn't sited in the floodway without meeting encroachment provisions, and notify FEMA when annexations bring new territory into a special flood hazard area.
140 backs the whole chapter with a cumulative civil penalty of $500 per day, running from the day a violation begins until compliance is achieved.
Violations & Fines
Building, filling, grading, or placing a manufactured home or non-highway-ready RV in a mapped special flood hazard area without SDCI (or SDOT, in the right-of-way) approval violates SMC 25.06.060. Under SMC 25.06.140, the City imposes a cumulative civil penalty of $500 per day for every day the violation continues until full compliance, on top of any other lawful enforcement action.
Frequently Asked Questions
Do I need a permit to build in a Seattle flood hazard area?
Which map decides if my Seattle property is in a flood zone?
What happens if I build without floodplain approval in Seattle?
Sources & Official References
Other rules in Seattle
Compare Seattle to another location·View the Washington environmental rules overview
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Flood Zones in Nearby Cities
How other cities in King County handle flood zones.