Bloomington, IL Environmental Rules: Flood Elevation Requirements (2026)

Bloomington City Code § 18-201 defines 'flood protection elevation' or FPE as the elevation of the base flood plus one foot of freeboard at any given location in the floodplain, and the base flood itself is the flood with a 1% chance of being equaled or exceeded in any year, commonly called the one-hundred-year flood. Section 18-301 ties the base flood elevation to the McLean County Flood Insurance Study dated July 16, 2008 for Sugar Creek, Little Kickapoo Creek, Skunk Creek and Goose Creek, to the Flood Insurance Rate Map for AH and AO zones, and to the best available federal, state, or other data for remaining A-zone floodplains, requiring a financed engineering study if no data exists.

Under § 18-701, any new building valued over $1,000, any substantially improved building, any structure enlarged more than 20% in floor area, and any manufactured home or long-term travel trailer placed in the floodplain must be protected below the flood protection elevation. Owners can meet this either by building on permanent fill with the lowest floor at or above the FPE, or by elevating the structure on stilts, piles, or walls with the lowest floor and all mechanical, electrical, and utility equipment at or above the FPE, with enclosed areas below that line limited to parking or access and fitted with flood-vent openings sized at one square inch per square foot of enclosed area.

Manufactured homes and long-term travel trailers must be elevated to or above the FPE and tied down under the state Mobile Home Tie-Down Act rules.