Federal Way, WA Environmental Rules: Flood Zones (2026)

FWRC 19.142.060(1) states that a floodplain development permit shall be obtained before construction or development begins within any area of special flood hazard established in FWRC 19.142.050(1), covering all structures, including manufactured homes, and all development including fill. The special flood hazard area itself is defined by reference to the Federal Insurance Administrator's 'Flood Insurance Study for King County, Washington and Incorporated Areas' dated August 19, 2020, and the accompanying Flood Insurance Rate Map, both on file at Federal Way City Hall under FWRC 19.142.050(1).

Routine landscaping maintenance, reroofing, siding replacement, and ordinary street or utility maintenance are excused from the permit under FWRC 19.142.060(2), but any other change to the land, including grading or new fill, needs the permit under subsection (3). Inside the more hazardous floodway subset of the flood hazard area, FWRC 19.142.160(1) bars any encroachment, fill, or new construction unless a registered engineer certifies it will not raise flood levels, and subsection (2) goes further for housing, prohibiting construction or reconstruction of residential structures within designated floodways except for repairs that do not enlarge the ground floor or that cost less than 50 percent of the structure's market value.

Applicants in zone AE must submit an elevation certificate (FEMA Form 81-31) showing the lowest floor elevation relative to mean sea level, and manufactured homes must be elevated at least one foot above base flood elevation on a permanent, anchored foundation per FWRC 19.142.140. A 'violation' under this chapter is defined broadly: a structure lacking the required elevation certificate or other compliance documentation is presumed noncompliant until the owner produces it.