Hawthorne, CA Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Base flood defined
- 1% annual chance (100-yr flood)
- Permit required
- Development permit, § 15.48.100
- Administrator
- Director of building and safety
- Standard
- Anchoring vs. flotation/lateral movement
- Utility rule
- HVAC/plumbing sited against flood entry
- Violation
- Misdemeanor, § 15.48.060
Summary
Any new construction or substantial improvement, including manufactured homes, sited in a Hawthorne flood-prone area must be anchored against flotation and lateral movement and built with flood-damage-resistant materials and protected utility equipment, under Hawthorne Code § 15.48.130 of the city's floodplain management chapter.
If a proposed building site is in a flood-prone area, all new construction and substantial improvements, including manufactured homes, shall: A. Be designed (or modified) and adequately anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. B. Be constructed: 1. With materials and utility equipment resistant to flood damage; 2. Using methods and practices that minimize flood damage; 3. With electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
Full Breakdown
48, the floodplain management regulations, defines the 'base flood' as the flood with a one percent annual chance of occurring, the familiar 100-year flood, based on the FEMA Flood Insurance Study for Los Angeles County and Incorporated Areas dated December 2, 1980, and its accompanying Flood Insurance Rate Maps and Flood Boundary and Floodway Maps, as amended. 130 then sets the construction standard itself: any proposed building site found to be in a flood-prone area must have its new construction and substantial improvements, including manufactured homes, designed and anchored to prevent flotation, collapse, or lateral movement from hydrodynamic and hydrostatic loads and buoyancy, built with flood-damage-resistant materials and construction methods, and equipped with electrical, heating, ventilation, plumbing, and air conditioning components sited or designed so flood water cannot enter or accumulate in them.
150 requires new water and sewer systems to be designed against flood infiltration and discharge. The chapter does not fix a specific freeboard number above base flood elevation; it works instead through this general anchoring, materials, and equipment-placement standard.
Violations & Fines
Section 15.48.060 makes it a misdemeanor to construct, locate, extend, convert, or alter any structure or land in a flood-prone area without full compliance with Chapter 15.48, on top of the citywide Section 1.20.010 penalty of up to a $1,000 fine, six months in jail, or both. The floodplain administrator, the director of building and safety, reviews every development permit application before issuance and can deny a permit that does not satisfy Section 15.48.130's anchoring and construction standards.
Frequently Asked Questions
Does Hawthorne require homes to be elevated a set height above base flood elevation?
What flood maps does Hawthorne use?
Who approves construction in a Hawthorne flood-prone area?
Sources & Official References
Other rules in Hawthorne
California rules heatmap·Compare Hawthorne to another location·View the California environmental rules overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.
Flood Elevation Requirements in Nearby Cities
How other cities in Los Angeles County handle flood elevation requirements.