Folsom, CA Environmental Rules: Flood Zones (2026)

32, under the city's Article XI, Section 5 charter authority, tying local regulation to the July 6, 1981 flood insurance study and FEMA's flood insurance rate maps for the city, on file at Folsom City Hall, 50 Natoma Street. 040 requires a development permit before any construction or development begins inside an area of special flood hazard, with the application showing the proposed elevation of the lowest floor of every structure and, for non-residential buildings, the elevation to which the structure will be floodproofed. The director of planning, inspections and permitting serves as floodplain administrator and reviews every permit to confirm the site is reasonably safe from flooding and that the project will not raise the base flood water surface more than one foot at any point.

050 sets the technical standards: new residential construction or substantial improvement must have its lowest floor, including any basement, at least two feet above the base flood elevation, certified by a California-registered engineer or land surveyor and verified by the chief building official; non-residential buildings may instead be floodproofed watertight below that elevation if certified by a licensed engineer or architect. Manufactured homes need the same two-foot elevation on an anchored permanent foundation, and recreational vehicles are exempt only if they stay fewer than 180 days and remain licensed and ready for highway use.

Inside a mapped floodway, new fill, construction or substantial improvement is prohibited unless an engineer certifies it will not raise flood levels, and where no floodway has been identified, Folsom imposes a 20-foot no-encroachment setback from the watercourse bank instead.