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Floodplain Management

In order to minimize the threat to life and property from flooding and erosion hazards, the Zoning and Codes Department administers Douglas County's floodplain management program (see Douglas County's Floodplain Management Regulations 12-328).  The program is managed in accordance with the Federal Emergency Management Agency's policies, to provide these benefits:

  • Provide a community effort of corrective and preventive measures for reducing flood damage to properties.
  • Intended to protect public health and safety, reduce damage to buildings and contents, prevent increases in flood damage from new construction, reduce the risk of erosion damage and protect natural and beneficial floodplain functions.
  • An opportunity for homeowners, renters, and business owners in our community to purchase federally-backed flood insurance through the National Flood Insurance Program. By implementing floodplain management activities, residents of Douglas County’s Unincorporated areas qualify for flood insurance premium rate reductions.


Douglas County Floodplain Map Viewer 
Kansas Floodplain Map Viewer

Selected Definitions:

  • 100 Year Floodplain - In a sense, the floodplain is the full extension of the creek. The 100-year floodplain is the land that is predicted to flood during a 100-year storm, which has a 1% chance of occurring in any given year. You may also hear the 100-year floodplain called the 1% annual chance floodplain or base flood.
  • 500 Year Floodplain - The "500-year flood" corresponds to an AEP of 0.2-percent, which means a flood of that size or greater has a 0.2-percent chance (or 1 in 500 chance) of occurring in a given year.
  • Elevation Certificate - An elevation certificate is a document prepared by a qualified engineer / surveyor which provides information on flood map location and additional information used to determine the proper flood insurance premium rates for a property. 
  • Letter of Map Change (LOMC) There are 4 types:
        1. Letter of Map Amendment (LOMA) A Letter of Map Amendment (LOMA) is an official amendment, by letter, to an effective National Flood Insurance Program (NFIP) map. A LOMA establishes a property's location in relation to the Special Flood Hazard Area (SFHA).
        2. Letter of Map Amendment - Out As Shown (OAS) Instructions. LOMA-OAS is a determination made by the Federal Emergency Management Agency (FEMA) for the property and/or buildings as to whether it is located within the Special Flood Hazard Area (SFHA).
        3. A Letter of Map Revision (LOMR) is the Federal Emergency Management Agency's (FEMA's) official modification to an effective Flood Insurance Rate Map (FIRM). LOMRs can result in a physical change to the existing regulatory floodway, the effective Base Flood Elevations (BFEs), or the Special Flood Hazard Area (SFHA).
        4. A Letter of Map Revision (A Letter of Map Revision Based on Fill (LOMR-F) is FEMA's modification of the Special Flood Hazard Area (SFHA) shown on the Flood Insurance Rate Map (FIRM) based on the placement of fill outside the existing regulatory floodway.
  • Base Flood Elevation - The computed elevation to which floodwater is anticipated to rise during the base flood. Base Flood Elevations (BFEs) are shown on Flood Insurance Rate Maps (FIRMs) and on the flood profiles.The BFE is the regulatory requirement for the elevation or floodproofing of structures. The relationship between the BFE and a structure's elevation determines the flood insurance premium.
  • CRS Community Rating SystemThe Community Rating System (CRS) is a voluntary, incentive-based community program that recognizes, encourages, and rewards local floodplain management activities that exceed the minimum standards of the National Flood Insurance Program (NFIP).
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Floodplain Regulations and Required Permitting

CRS Community Rating System

Important Contacts

Floodplain Documents