Pasco, WA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Residential freeboard
- 1 foot above base flood elevation
- Critical facilities
- 3 feet above BFE or 500-year flood height
- Enclosed space venting
- 1 sq in per sq ft of enclosed area, min. 2 openings
- Manufactured homes
- Same 1-foot elevation, anchored per PMC 24.20.020(2)
- Nonresidential option
- Engineer-certified floodproofing to 1 ft above BFE
Summary
New and substantially improved homes in Pasco's mapped flood hazard areas must have their lowest floor, including any basement, built at least one foot above base flood elevation. Manufactured homes and nonresidential buildings face the same one-foot freeboard standard under PMC 24.20.080-.100.
New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to one foot or more above base flood elevation. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of flood waters.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 4837, passed May 4, 2026).
Full Breakdown
080(2)). 100. 090). 130 requires their lowest floor at three feet above base flood elevation, or to the 500-year flood height, whichever is higher, plus floodproofing to keep toxic substances from displacing into floodwaters. 060 still requires the Building Inspector to review permits for reasonable flood safety and warns that failing to elevate at least two feet above the highest adjacent grade can trigger higher federal flood insurance rates.
Violations & Fines
Building a lowest floor below the one-foot freeboard in PMC 24.20.080(1), or enclosing space below it without the required flood-vent openings under PMC 24.20.080(2), is a permit violation the Building Inspector can flag on inspection. Floodproofing a nonresidential building without the engineer's certification required by PMC 24.20.090(3) leaves the owner without a valid alternative to elevation and exposed to higher insurance premiums, since coverage is rated as if the building sat one foot below its actual floodproofed level.
Frequently Asked Questions
How high above base flood elevation must a new Pasco home be built?
Can I finish a basement or crawlspace below the elevated floor?
Does floodproofing let a business skip the elevation requirement?
Sources & Official References
Other rules in Pasco
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