Downey, CA Environmental Rules: Flood Zones (2026)

Downey's floodplain management chapter, adopted under the authority of Government Code §§ 65302, 65560, and 65800, exists to keep new development out of harm's way and to keep the City's flood insurance program intact. Section 8700.04 makes the chapter apply to all areas of special flood hazard within city limits, and § 8700.05 ties that boundary to a specific technical document: the "Flood Insurance Study for the City of Downey," with its accompanying Flood Insurance Rate Map dated July 6, 1998 and all later revisions, on file with the Engineering Division at 11111 Brookshire Avenue.

Before anyone can start new construction, development, or a substantial improvement inside one of those mapped areas, § 8710.01 requires a building or grading permit, applied for on City forms. The application has to include scaled plans showing the proposed elevation of the lowest floor (or the floodproofing elevation) relative to mean sea level, per § 8710.02, and pay the fee set by City Council resolution under § 8710.03. The Building Official reviews the application for compliance with the chapter and issues the permit once the fee is paid and the plans check out.

Section 8700.07 makes compliance with both the floodplain and grading portions of the chapter mandatory, and treats any failure to meet the chapter's requirements, including violated conditions or safeguards, as a misdemeanor. Property owners who disagree with a floodplain boundary determination or want relief from a requirement can seek a Flood Zone Exception through the Board of Building Appeals under § 8720.