Novato, CA Environmental Rules: Flood Elevation Requirements (2026)

Section 5-31.008 of the Novato Municipal Code, part of the City of Novato's Flood Damage Prevention Requirements in section 5-31, sets the construction standards for every area of special flood hazard inside the city. Under subsection a.3.(a), new construction and substantial improvement of any structure must have the lowest floor, including a basement, elevated to or above the base flood elevation. When construction starts, a registered professional engineer or surveyor certifies the elevation of the lowest floor, and the certification goes to the floodplain administrator in the form the administrator prescribes. Section 5-31.006 names the city engineer as floodplain administrator.

Shallow-flooding zones use a different measure. In Zone AH, AO or VO, subsection a.3.(b) requires the lowest floor to sit above the highest adjacent grade at least as high as the depth number printed in feet on the FIRM, or at least two feet if the FIRM prints no depth number.

Nonresidential structures have a floodproofing option under subsection a.3.(c). The building and its attendant utility and sanitary facilities must be watertight, with walls substantially impermeable to the passage of water one foot above the base flood level, must have structural components that resist hydrostatic and hydrodynamic loads and buoyancy, and must carry a certification from a registered professional engineer or architect. Fully enclosed areas below the lowest floor need openings to equalize flood forces: a minimum of two openings with a total net area of not less than one square inch for every square foot of enclosed area, with the bottom of every opening no higher than one foot above grade, unless the design is certified by an engineer or architect.

Two definitions in section 5-31.007 set the reach of the rule. The base flood is the flood with a one percent chance of being equalled or exceeded in any given year. A substantial improvement is any repair, reconstruction or improvement costing 50 percent or more of the structure's market value. The hazard areas come from the Flood Insurance Study for the City of Novato, California, Marin County, dated April 3, 1984, or the most recent study, kept on file with the Engineering Division of the Department of Community Development. New and replacement manufactured homes must also be elevated so the lowest floor is at or above the base flood elevation.