Ontario, CA Environmental Rules: Flood Zones (2026)

302 and kept on file with the City Engineer at 303 East "B" Street. 401 requires a development permit before construction or development begins in any mapped hazard area, with the application submitted on Floodplain Administrator forms and including, at minimum, scaled plans showing the location, dimensions, and elevation of the site, proposed structures, fill, storage of materials, and drainage facilities; the applicant must state the proposed elevation of the lowest habitable floor relative to mean sea level, the elevation to which any structure will be floodproofed, and the extent to which any watercourse will be altered or relocated.

402 designates the Development Director as the City's Floodplain Administrator, responsible for granting or denying these development permits. 303 requires full compliance with the chapter before any structure or land is constructed, located, extended, converted, or altered in a mapped hazard area, and makes noncompliance a misdemeanor while preserving the City Council's authority to take other lawful action to prevent or remedy a violation. 304 applies whichever imposes the more stringent restriction.