St. Peters, MO Environmental Rules: Flood Elevation Requirements (2026)

This specific standard applies wherever base flood elevation data has been provided under Section 410.150(B), and it works alongside the general standards in Section 410.150 that already bar new construction, fill, or other development in a numbered A or AE zone before a floodway is designated unless it is shown the project will not raise the base flood's water surface elevation more than one foot anywhere in the community. For non-residential construction, Section 410.160(A)(2) offers a compliance alternative to elevation: a commercial, industrial, or other non-residential structure, including a manufactured home, may instead be floodproofed below the base flood elevation so the structure is watertight, with walls substantially impermeable to water and structural components able to resist hydrostatic and hydrodynamic loads and the effects of buoyancy, certified by a registered professional engineer or architect and reported to the Floodplain Manager under Section 410.130(A)(9).

The Floodplain Manager, per Section 410.130, must verify and keep a record of the actual lowest-floor elevation of every new or substantially improved structure. A structure remodeled or enlarged may skip the elevation requirement only if the cumulative value of all work in the prior five years stays under 50% of its current market value; crossing that threshold triggers full compliance with Section 410.160(A) under Section 410.150(G).