Mission Viejo, CA Environmental Rules: Flood Zones (2026)

100 of the Municipal Code, adopted under Government Code §§ 65302, 65560 and 65800, governs every parcel within an area of special flood hazard as mapped by the Flood Insurance Rate Map dated February 5, 1992, and later revisions kept on file at City Hall (Sec. 320). Before any construction, mining, dredging, filling, grading, paving or drilling begins in one of those areas, the property owner must obtain a development permit from the floodplain administrator, a role assigned to the director of public works (Sec.

420). The permit application must show, on scaled plans, the elevation of the site, existing or proposed structures, fill and drainage facilities, plus the proposed elevation of the lowest floor relative to mean sea level, the elevation to which any structure will be floodproofed, and a description of any watercourse alteration (Sec. 410). The administrator reviews every permit to confirm site safety from flooding, that other required state and federal permits are in hand, and that the project will not raise the base flood water surface more than one foot when combined with other development (Sec.

430). Failure to comply with the chapter, including violating any permit condition, is a misdemeanor under Sec. 330, separate from the citywide general penalty in Sec. 230. Floodways carry an added restriction: encroachments including fill and new construction are prohibited unless a registered engineer certifies no increase in flood levels during the base flood (Sec. 550). Property owners who believe the floodplain administrator misapplied a mapped boundary or permit requirement can appeal to the city council under Division 6 of the chapter.