Kennewick, WA Environmental Rules: Flood Elevation Requirements (2026)

060 sets the construction standards that apply once a lot falls inside the Federal Insurance Administration's mapped Special Flood Hazard Area under the City's Flood Insurance Study (originally dated May 5, 1981, revised June 15, 1994). 060(2)(a)(i), new residential construction and substantial improvements must have the lowest floor, including any basement, elevated one foot above the base flood elevation (BFE); any fully enclosed area below that floor must either be prohibited or fitted with flood vents meeting a minimum-opening formula of one square inch of net open area per square foot of enclosed space, with vent bottoms no higher than one foot above grade.

060(2)(b) face the same one-foot freeboard, or must be dry-floodproofed and certified watertight by a Washington-registered professional engineer. 060(2)(e). Manufactured homes must be elevated the same one foot above BFE and anchored against flotation and lateral movement. Floodways are off-limits to encroachment, including fill, unless a licensed civil engineer certifies via hydraulic analysis that the work will not raise flood levels. 040(2) that must include site plans, elevation drawings referenced to mean sea level, and (for floodproofed nonresidential buildings) a Washington-licensed engineer's certification. 040(3) and can revoke a permit and order a structure vacated or demolished if conditions are not met.