Floodplain Development Permit

With more than 40% of St. Charles County classified as flood-prone land, the County’s floodplain development ordinance is critical to protect life and property, reduce disaster impacts and qualify for Federal disaster assistance, and allow County property owners to participate in the National Flood Insurance Program. The County’s participation in this national program since 1978 has allowed property owners to purchase private flood insurance when required by their lenders for their federally back mortgages. The State Emergency Management Agency administers the National Flood Insurance Program in Missouri.

How Do I Apply?

Please visit the Land Development & Zoning Applications section of our Citizenserve Citizen Access Portal.

When Do I Need a Floodplain Development Permit?

St. Charles County requires floodplain development permits for practically all construction, improvements, demolition, or earthmoving within any area defined by the effective Flood Insurance Rate Maps and Studies as floodway fringe, density floodway, or floodway. Floodplain development permits are required even in cases when a building permit would not. For example, sidewalk construction, building a fence, replacing a window, installing electrical service, constructing a driveway or street, or reroofing a structure all require a floodplain development permit. New construction or substantial improvement of existing structures must construct or newly-elevate the finished floor elevation of the lowest floor to at least 1.0 feet higher than the base flood elevation. The County recommends elevating higher than the required minimum. When not taken out in conjunction with any building permit, Floodplain Development Permits will be in effect for 2 years from the date of issuance.

How Do I Know If My Project is Located Within a Regulated Flood Zone?

To determine if your project is located within a floodway, floodway fringe, or density floodway, you can:

How Do I Apply for a Floodplain Development Permit?

Please visit the Land Development & Zoning Applications section of our Citizenserve Citizen Access Portal.

What Will I Need to Submit?

  • Plans and specifications for proposed construction, fill area, or grading. This should include an elevation certificate based on construction drawings from a surveyor or engineer licensed by the State of Missouri.
  • An indication whether the work would be located in designated floodway fringe or floodway
  • Identification of the existing base flood elevation (BFE) for all areas to be filled on the property, as well as the elevation for all structures to be modified, including any crawl space or basement, mechanical equipment such as heating and cooling, electrical panels, or garages
  • County Assessor’s estimated current market value for the structure
  • Once any new or newly-elevated structure is completed to the lowest floor, submission of an elevation certificate, completed by a registered land surveyor or engineer, and showing that the work meets the minimum elevation standards.

Depending on the specific work to be undertaken in a floodplain, the application might also need to include:


Complete applications must include payment of the fee specified in Section 425.020.D of the Unified Development Ordinance.