St. Louis County, MO Environmental Rules: Flood Zones (2026)
FEMA flood zone rules in St. Louis County, MO, also called floodplain regulations or special flood hazard area (SFHA) rules, determine flood insurance requirements and elevation standards for new construction.
Key Facts
- Permit required
- floodplain development permit
- Administrator
- Director of Highways and Traffic
- Penalty
- up to $1,000 per day
- Appeal path
- BZA, then Circuit Court
- Seller disclosure
- written, before sale/conveyance
- Nonconforming use lapse
- 12 consecutive months
- Current FIRM adopted
- February 4, 2015
Summary
Chapter 1008 of the St. Louis County Code bars any development in the county's mapped A, AE, AO, and AH flood zones without a floodplain development permit from the Director of Highways and Traffic. The chapter covers all unincorporated land on the FIRM index panels adopted February 4, 2015, and a violation carries a fine of up to $1,000 per day under Section 1008.090.
1. Lands to which chapter applies. This chapter shall apply to all lands within unincorporated St. Louis County identified as numbered and unnumbered A zones, AE, AO, and AH Zones, on the Flood Insurance Rate Map (FIRM) for St. Louis County on Index panels 29189CIND1A, 29189CIND2A and 29189CIND3A dated February 4, 2015 as amended, and any future revisions thereto. In all areas covered by this chapter, no development shall be permitted except after the issuance of a floodplain development permit, granted by the Director of Highways and Traffic or their duly designated representative under such safeguards and restrictions as the Floodplain Administrator or their designated representative may reasonably impose for the promotion and maintenance of the general welfare, health of the inhabitants of the community... No person shall violate any of the provisions of this chapter. Any person who violates a provision of this chapter or fails to comply with any of its requirements shall, upon conviction thereof, be fined not more than one thousand dollars ($1,000.00). Each day such violation continues shall be considered a separate offense.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 85 | Traffic: Supplement 80).
Full Breakdown
030 applies the chapter to every numbered and unnumbered A, AE, AO, and AH zone shown on the County's Flood Insurance Rate Map, and it bars locating, extending, converting, or structurally altering any development in those zones without full compliance, while preserving any stricter easement, covenant, or deed restriction already in place. 050's flood hazard reduction standards, which require flood-resistant construction materials, anchored foundations, and elevated or floodproofed utilities. A property owner who is denied a permit, or who wants a variance from these standards, can appeal to the Board of Zoning Adjustment under Chapter 1004 and further appeal that decision to the St.
060. 090 penalty. 080, but it cannot be expanded or altered in a way that increases the nonconformity, and utilities must report to the Zoning Enforcement Officer when service to a nonconforming use lapses for twelve consecutive months.
Violations & Fines
Violating any provision of Chapter 1008, including building without a floodplain development permit, is punishable under Section 1008.090 by a fine of up to $1,000 upon conviction, with each day the violation continues counted as a separate offense, in addition to any other lawful County enforcement action. The disclosure violation in Section 1008.070 carries its own $1,000 fine but is expressly excluded from the Section 1008.090 penalty stack, so the two cannot be charged together for the same transaction.
Frequently Asked Questions
Do I need a permit to build in a St. Louis County flood zone?
What happens if I build in the floodplain without a permit?
Can I appeal a denied floodplain permit or ask for a variance?
Do sellers have to disclose flood zone status to buyers?
Sources & Official References
Other rules in St. Louis County
Compare St. Louis County to another location·View the Missouri environmental rules overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.