Yolo County, CA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard requirement
- 1 ft above base flood elevation
- Zones covered
- AE, AH, A1-30, and A zones
- AO zone standard
- Depth number plus 1 ft, or 3 ft
- Permit required first
- Development Permit, § 8-4.403
- Enforcing official
- Floodplain Administrator
- Violation classification
- Misdemeanor, Title 1 fines
- Appeal window
- 15 calendar days
Summary
In special flood hazard areas, Yolo County's flood damage prevention ordinance requires new and substantially improved residential structures in AE, AH, and A1-30 zones to elevate the lowest floor at least one foot above the base flood elevation, with a Development Permit required first.
(c) Elevation and floodproofing.
(1) Residential construction, new or substantial improvement, shall have the lowest floor, including basement:
(i) In AE, AH, A1-30 Zones, elevated at least one (1) foot above the base flood elevation.
(ii) In an AO zone, elevated above the highest adjacent grade to a height exceeding the depth number specified in feet on the FIRM by at least one (1) foot, or elevated at least three (3) feet above the highest adjacent grade if no depth number is specified.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-21: Supplement 2026 S-21 includes: Local legislation current through Ord. 1584, effective June 25, 2026).
Full Breakdown
501(c)(1)(i), Standards of construction, Elevation and floodproofing. 201 as the water surface elevation shown on the Flood Insurance Rate Map for a flood with a one percent annual chance of being equaled or exceeded, the 100-year flood. 402(c). Before framing begins, a registered professional engineer or licensed land surveyor must certify the lowest floor elevation, verified by the County Building Official or designee, and that certification goes to the Floodplain Administrator, a role held by the Director of the Yolo County Community Services Department or designee.
501(c)(2)). 403, which requires plans showing base flood elevation data, proposed lowest-floor elevation relative to mean sea level, and, for crawl-space foundations, flood-vent opening calculations meeting FEMA Technical Bulletins 1-93 and 7-93.
Violations & Fines
Violating this chapter is a misdemeanor that can carry fines under Title 1 of the Yolo County Code (§ 8-4.406(a)). Noncompliance triggers a written notice of violation describing the defect and the remedial steps required; ignoring that notice is itself a public nuisance and a separate misdemeanor, remediable by injunction or other civil action brought by the County. The Floodplain Administrator can also suspend or revoke a Development Permit for noncompliance, forcing an immediate halt to work, and a permittee gets 15 calendar days to appeal a suspension or revocation under § 8-4.405 before the Board of Supervisors.
Frequently Asked Questions
How high above base flood elevation must a house be built in Yolo County?
Can a nonresidential building be floodproofed instead of elevated?
What happens if someone builds in a Yolo County flood hazard area without a permit?
Sources & Official References
Other rules in Yolo County
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