Environmental Rules in St. Charles County, MO (2026)
5 rules for unincorporated St. Charles County, Missouri.
Verified from official government sources
Stormwater Management
New subdivisions in unincorporated St. Charles County must install separate storm sewers and, once they disturb an acre or more, treat stormwater for water quality before it leaves the site. Code § 410.410 sets the design standards, and lots of three acres or larger are exempt from that water-quality requirement, while detention for flood and channel protection is tested separately by runoff volume.
St. Charles County Stormwater Management Rules
Some RestrictionsSt. Charles County Code § 410.410
A. In addition to the installation of curbs and gutters along the streets as required by this Chapter, storm sewers shall be required... The stormwater drainage system shall be separate and independent of the sanitary sewer system. ... D.1.b. Water quality treatment is required for all new subdivision developments that disturb an area one (1) acre or greater, including subdivision developments ...
Erosion Control
St. Charles County requires a land disturbance permit before anyone disturbs 5,000 square feet or more of unincorporated ground for non-agricultural development. The Department of Community Development issues the permit, plan review runs $50 plus $50 per acre up to ten acres, and violators face a misdemeanor charge with fines up to $1,000 per day the disturbance continues unpermitted.
St. Charles County Land Disturbance Permit Rule
Some RestrictionsSt. Charles County Code §§ 412.020, 412.040
Any person, firm, corporation or business proposing to remove any ground vegetation, to disturb or fill the land or to store soil within unincorporated St. Charles County shall apply to the Department of Community Development for approval and issuance of a land disturbance permit. State and Federal permit conditions that are more stringent than the requirements set forth herein shall govern. .....
Flood Zones
In the Floodway Fringe Overlay District, new construction and substantial improvements on land mapped Zone A or Zone AE must have the lowest floor elevated one foot above the base flood elevation. St. Charles County Code § 405.355(B) sets that standard, with a floodproofing alternative for non-residential buildings certified by a registered engineer.
St. Charles County Floodway Fringe Elevation Rules
Some RestrictionsSt. Charles County Code § 405.355(B)(1)-(2)
B. Standards For The Floodway Fringe Overlay District. 1. Require that all new construction and substantial improvements of residential structures, including manufactured homes within Zone A and Zone AE on the County's FIRM, have the lowest floor (including basement) elevated to one (1) foot above the base flood elevation. 2. Require that all new construction and substantial improvements of non...
Boat Dock Permits
Boat docks, marinas and piers are a permissive use only in St. Charles County's Riverfront (RF) and Park Recreational (PR) zoning districts along the Missouri and Mississippi Rivers. In the RF District a dock or marina lot needs at least 300 feet of river frontage and a 30-foot setback from property lines. The Division of Planning and Zoning enforces these limits.
St. Charles County Boat Dock Permit Rules
Some RestrictionsSt. Charles County Code § 405.120(B)(2), (D)(2)-(7)
B. Permissive Uses. ... 2. Boat docks, marinas and piers. ... D. Height And Area Regulations. 1. No minimum site area for all uses except for riverboat gambling vessels. The minimum site area for riverboat gambling vessels shall be no less than twenty-five (25) acres. 2. The minimum frontage along a major river shall be three hundred (300) feet. 3. The maximum height for permitted uses in this ...
Flood Elevation Requirements
New homes and additions in unincorporated St. Charles County's mapped Zone A and Zone AE must sit with the lowest floor, including any basement, elevated one foot above base flood elevation. Non-residential buildings can dry-floodproof instead, but only with a licensed engineer's certification and a floodplain development permit from Planning and Zoning.
St. Charles County Flood Elevation Rule
Some RestrictionsSt. Charles County Code § 405.355(B)(1)-(2)
1. Require that all new construction and substantial improvements of residential structures, including manufactured homes within Zone A and Zone AE on the County's FIRM, have the lowest floor (including basement) elevated to one (1) foot above the base flood elevation. 2. Require that all new construction and substantial improvements of non-residential structures within Zone A and Zone AE on th...
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