Antioch, CA Environmental Rules: Flood Zones (2026)

Article 20 of the Antioch Municipal Code implements local floodplain regulation. 2004 adopts by reference the Flood Insurance Study for Contra Costa County and its Flood Insurance Rate Maps and Flood Boundary and Floodway Maps, both dated June 16, 2009, plus all later revisions; the underlying study is kept on file at the Community Development Department, Engineering Division, 200 'H' Street. Any parcel inside a mapped area of special flood hazard is subject to the article regardless of what the base zoning district otherwise allows.

2005 makes the City Engineer the Floodplain Administrator and requires a development permit application, on the city's own forms, before construction, filling, grading, dredging, paving, or any other man-made change to the land begins. Applicants must show the proposed elevation of the lowest floor, including any basement, relative to mean sea level, the elevation to which the structure will be floodproofed, and, if a watercourse will be altered or relocated, the extent of that alteration. The Floodplain Administrator confirms the project will not raise the base flood's water surface elevation more than one foot anywhere in the city, that all other state and federal permits are in hand, and that the site is reasonably safe from flooding. 2012.