DepartmentsGovernmentClick to HomeExplore Johnston
Help Center
Click to Home

Go To Search
Emergency Alerts

GIS / Mapping
Preliminary FEMA Floodplain Maps Released
In order to ensure all Johnston properties are able to purchase flood insurance for their properties, if necessary, the City of Johnston participates in the National Flood Insurance Program (NFIP).

As part of this program, the City is required to maintain ordinance requirements limiting/controlling development within designated flood hazard areas which are determined by the FEMA FIRM maps (for reference these requirements are contained within Chapter 169 of the Zoning Ordinance http://www.cityofjohnston.com/DocumentCenter/View/296. The current FIRM maps regulating properties within Johnston were adopted on July 19, 2000.  However, over the last couple of years FEMA has been working to update all FIRM maps within Johnston based upon:

    • Updated hydrologic and hydraulic analysis of portions of Little Beaver Creek, affecting flood hazard areas generally north of NW 70th Avenue and east of NW 86th Street; and,
    • Re-delineation of flood hazard areas using updated topographic information, affecting all flood hazard areas within Johnston.  The 2000 FIRM maps were prepared using 10 foot topographic contour data, while the preliminary maps use 2 foot topographic contour data.

    As a result of this work, FEMA has published preliminary FIRM maps and an FIS for Johnston dated June 17, 2015.  In order to continue to participate in the NFIP, the City is required to officially adopt these updated maps, with this approval expected in late 2016 or early 2017.  However, before FEMA will issue final FIRM maps, they provide communities and property owners the opportunity to appeal the proposed flood hazard information presented on the Preliminary FIRM maps.  All appeals must be filed with FEMA before May 31, 2016.  It is important to note that the sole basis for appeals is the possession of knowledge or information indicating that the proposed flood hazard determinations are scientifically or technically incorrect.  As such, all appeals will need to be studied and prepared by a licensed engineer.

    The City of Johnston has reviewed the preliminary FIRM maps, and is not intending at this time to submit an appeal; however, we want to afford all affected property owners the ability to appeal should they believe they have scientific or technical information that would affect the flood hazard determination of their properties.  To that end, to allow you to review the effect of the updated FIRM maps on your property, the following information is available:

    A link to the Preliminary FIRM Map and Flood Study for Johnston dated June 17, 2015:


    Preliminary Flood Study for Polk County – Volume 1
    Preliminary Flood Study for Polk County – Volume 2
    Preliminary Flood Study for Polk County – Volume 3

    Panel Guide – Johnston Maps are provided on multiple panels, this is a guide to the location of each panel (panels are provided in the links below):

    A map, prepared by City staff, that generally shows the comparison of the 2000 FIRM maps and the preliminary 2015 FIRM maps by identifying locations of areas added to or deleted from flood designated areas.  Please note this is not an official FEMA map, nor should it be used to determine if your property is or is not within a flood hazard area, rather it’s been prepared to assist you in determining the general affect of the preliminary FIRM maps: http://arcg.is/1Rr39mE

    Links to resources and information pertaining to the National Insurance Flood Program: http://www.cityofjohnston.com/Index.aspx?NID=111

    A Summary of Actions pertaining to previously approved Letters of Map Revisions (LOMR) or Letters of Map Amendments (LOMA).  LOMR and LOMA’s are property specific studies prepared to show that the property and/or structures on the property are located above the flood designated areas shown the FIRM maps.  This summary notes how previously approved LOMA and LOMR’s, issued between July 19, 2000 and June 17, 2015, where addressed on the preliminary FIRM maps for Johnston; and, Summary of Map Actions

    Criteria for Appeals of the Flood Insurance Rate Map. Criteria for Appeals

    A copy of the preliminary FIRM maps and Flood Study, and all of the information noted above, is also available for review in the Community Development Office at Johnston City Hall, located at 6221 Merle Hay Road.  You may stop in anytime during regular office hours from 8 a.m. – 5 p.m. to review this information.  Should you desire to discuss this information with a staff member, it is suggested that you schedule an appointment in advance by calling 515-727-7778.

    Any interested party who wishes to appeal should present the data that tend to negate or contradict the FEMA finding to the City of Johnston by no later than April 29, 2016, to allow time for the City to review the information, consolidate it with any other appeals, and transmit it to FEMA prior to their deadline.  All submitted appeals should follow the FEMA criteria for appeals.  If you do not already have flood insurance through the NFIP, I strongly encourage you to contact your insurance agent to discuss the options best suited for your property.  Should you have any questions, please feel free to contact David Wilwerding at 515-727-7775 or by email at .