Environmental Rules in St. Louis County, MO (2026)
6 county-level rules, plus city-specific rules for 1 city in St. Louis County, Missouri.
Verified from official government sources
Stormwater Management
Before grading or disturbing land anywhere in unincorporated St. Louis County, from a single subdivision lot to a commercial site, the owner needs a land disturbance permit from the Department of Transportation and Public Works. Section 1005.230 bars any grading that would redirect a watershed, and Section 1114.200 caps cut and fill slopes at a 3:1 ratio unless the county specifically approves a steeper design.
St. Louis County Stormwater and Land Disturbance Rules
Some RestrictionsSt. Louis County Code § 1005.230 / § 1114.200 (Section 201.1)
1005.230 - Grading. —1. Where the preliminary plat indicates that extensive grading and compaction are probable, the Department of Transportation and Public Works may require the submission of additional information and modifications in the proposed plat before the developer may grade any land to be subdivided. 2. A land disturbance permit is required from the Department of Transportation and P...
Erosion Control
St. Louis County's Land Disturbance Code sets hard deadlines for stabilizing bare soil on active construction sites, plus sediment-trapping design standards.
Erosion & Sediment Control Rules
Some RestrictionsSection 1114.200, § 201.2(1) SLCRO
Permit holder shall install temporary stabilization when soil disturbing activities will cease on any portion of the site and are not planned to resume for a period exceeding fourteen (14) calendar days. Temporary stabilization must be initiated immediately upon knowing the duration is more than fourteen (14) days. Temporary stabilization must be completed within seven (7) calendar days.
Flood Zones
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.
St. Louis County Floodplain Development Permit Rule
Significant RestrictionsSt. Louis County Code §§ 1008.030, 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 c...
Boat Dock Permits
Non-commercial boat docks are a permitted, by-right use in St. Louis County's "FP" Flood Plain District, and marinas, boat docks, and ramps are permitted outright in the "PS" Park and Scenic District, so a private dock on qualifying waterfront land in unincorporated county territory doesn't need a special zoning permit.
St. Louis County Boat Dock Zoning Rule
Some RestrictionsSt. Louis County Code § 1003.101; § 1003.103
3.Permitted land uses and developments. The following land uses and developments are permitted in this district:(1)Boat docks for other than commercial or industrial use.(2)Farming.(3)Golf courses.(4)Hunting, fishing and propagation of wildlife...This section is therefore necessary to protect human life and health; to minimize expenditure of public money for costly flood control projects...2.Pe...
Vehicle Idling Restrictions
St. Louis County bans letting a vehicle engine idle for more than three consecutive minutes while parked, standing, or stopped, under the county's air pollution nuisance code. Emergency vehicles are exempt, as are engines running a loading, unloading, or processing device, and violations are punishable under the county's general air pollution penalty of up to $1,000 or a year in jail.
Vehicle Idling Time Limit (St. Louis County)
Some RestrictionsSLCRO Section 612.340.2
It is unlawful for any person, firm or corporation to permit or cause the escape of such quantities of soot, cinders, noxious acids, fumes and gases or other particulate matter from whatever source in such place or manner as to be detrimental to any person or to the public or to endanger the health, comfort and safety of any such person or the public, or in such manner as to cause or have a ten...
Flood Elevation Requirements
Where the County has mapped a base flood elevation on a numbered A, AE, or AH zone, Section 1008.050 requires new construction and substantial improvements to elevate the lowest floor, including any basement, to at least one foot above that base flood elevation. Non-residential buildings may floodproof to that same one-foot freeboard instead, but a registered engineer or architect must certify the floodproofing meets the standard.
St. Louis County Base Flood Elevation Freeboard Rule
Some RestrictionsSt. Louis County Code § 1008.050
2. Specific standards. (1.) In all areas identified as numbered and unnumbered A zones, AE, and AH Zones, where base flood elevation data have been provided, as set forth in Section 1008.050-1(2.), the following provisions are required: (a.) Residential construction. New construction or substantial improvement of any residential structures, including manufactured homes, shall have the lowest fl...
Environmental Rules by City in St. Louis County
1 cities in St. Louis County have their own environmental rules rules. Each link goes to that city's dedicated page with code citations.
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